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CYLINDER BORING 
REAMING AND 
GRINDING 





CYLINDER BORING 
REAMING AND 
GRINDING 


A TREATISE ON THE TYPES OF MACHINES, 
CUTTING TOOLS AND FIXTURES USED FOR 
BORING AND REAMING CYLINDERS, AND THE 
PRACTICE IN GRINDING THE CYLINDERS OF 
GASOLINE ENGINES 


BY 

FRANKLIN D. JONES 

ASSOCIATE EDITOR OF MACHINERY 
AUTHOR OF “MECHANICAL DRAWING,” “THREAD CUTTING METHODS/’ 
“MECHANISMS AND MECHANICAL MOVEMENTS,” 

“TURNING AND BORING,” Etc. 


FIRST EDITION 

FIRST PRINTING 



o > •> 


> 




NEW YORK 

THE INDUSTRIAL PRESS 

London: THE MACHINERY PUBLISHING CO., Ltd. 
1921 




'Tel l£^0 
• Jb 



in . umiiig mill i 


Machinery is notea 

{or erUerpriae and 
thoroughness. 


Machinery 

is all for 







Copyright, 1921, The Industrial Press, Publishers of Machinery, 
140-148 Lafayette Street, New York City 

MAR 14 1921 

© Cl A 60999 4 














tq. aix ay 


rd 


PREFACE 


In the making of steam engines, and more especially in 
the manufacture of gasoline engines, or other motors of the 
internal combustion type, the finishing of the interior sur¬ 
faces or bores of the cylinders is an important operation. 
A true cylinder is essential in a steam engine, but it is even 
more vital in an oil or gas engine, because of the close rela¬ 
tion between the proper degree of compression and the 
power developed by the motor. The object of this book is 
to deal comprehensively with the different methods, tools, 
fixtures and machines used for cylinder work. As the most 
highly developed cylinder machining methods are found in 
automobile plants, the equipment and practice of these 
plants is a special feature of this treatise. In factories 
producing motors by the thousand, it has been necessary 
to do the work rapidly as well as accurately, which accounts 
for many of the interesting tools and machines which have 
been developed. 

As cylinders vary greatly in size and are used for many 
different purposes, naturally many different forms of tools 
and types of machines are employed for machining the 
interior cylindrical surface or “bore,” as it is commonly 
called. Many cylinders are bored on standard machine 
tools which are adapted to other operations, but the exten¬ 
sive use of cylinders in some lines of manufacture has led to 
the development of special tools and machines designed ex¬ 
clusively for cylinder work. 

The most interesting practice in machining cylinder bores 
is found in automobile factories and other plants making 
motors of the internal combustion type, owing to the fact 
that such motors require a compressed charge, and a lack or 
loss of compression causes a decided reduction in the power 
of a motor. For this reason, it is necessary to finish motor 


V 



VI 


PREFACE 


cylinders accurately as to diameter and as truly cylindrical 
as it is practicable to make them, in order to secure a mini¬ 
mum of clearance between the piston and the cylinder wall. 
The problem of tool designers, manufacturers of reamers or 
cylinder boring machines, and others concerned with effi¬ 
cient methods of finishing motor cylinders, has been to 
secure not only accurate work, but also maximum produc¬ 
tion. Since the machines and tools which have been devel¬ 
oped for use in automobile plants are exceptionally interest¬ 
ing, this class of equipment and the important variations 
in practice will be described completely. While the cylinders 
of steam engines, pumps, air compressors, etc., require less 
accuracy as a class than cylinders of internal combustion 
motors, a few examples typical of this kind of cylinder 
work, will be included to illustrate the general procedure 
and some of the different types of tool equipment used. 
No attempt will be made to deal with every possible method 
of machining interior cylindrical surfaces, this treatise 
being confined principally to the machines that have been 
designed primarily for cylinder work and to the auxiliary* 
tools used in conjunction with these machines. 


F. D. J. 


CONTENTS 


Chapter I 

CYLINDER BORING AND REAMING 

Classes of Boring Machines—Combination Bor¬ 
ing and Milling Machine—Boring and Reaming on 
Single-spindle Machines—Speeds and Feeds for 
Reaming—Heat-treatment after Rough Boring— 
Scleroscope Test before Boring—Lapping Cylinders 
—Rolling or Planishing Cylinder Bores—Tool for 
Cylinder Rolling—Radial Cylinder Boring Attach¬ 
ment—Boring Large Cylinders—Grinding Boring 
Tools—Portable Boring-bars. 

Chapter II 

CYLINDER BORING AND REAMING TOOLS 

Cutter-heads for Rough-boring—Floating Types 
of Reamers—Machining Head of Cylinder—Adjust¬ 
able Reamers—Floating Parallel Reamer—Shell 
Reamers—Combination Boring and Reaming Tools 
—Cutting Edges of Tools—Pilots for Cylinder 
Reamers. 34-60 


PAGES 


1-33 


Chapter III 

CYLINDER BORING AND REAMING FIXTURES 

Boring Fixture with Movable Locating Pins— 

Fixture with Wedge and Cam-operated Clamps— 
Clamping Wedges—Sliding Casting in and out of 
Fixture—Fixtures for Open-end Cylinders—Fix¬ 
ture with Removable Work-holding Slides—Index¬ 
ing Fixture for Single-spindle Machine... 61-72 


vii 





CONTENTS 


viii 


Chapter IV 

CYLINDER GRINDING 

PAGES 

Grinding vs. Reaming—Eccentric-head Cylinder 
Grinder—Cylinder Grinder with Grinding Head 
Cross Adjustment—Rotation of Wheel-head and 
Feeding Movement of Cylinder—Circulating Water 
through Cylinder Jacket — Circulating Steam 
through Jacket—Wet and Dry Methods of Grinding 
—Allowances for Cylinder Grinding—Airplane En¬ 
gine Cylinders—Cylinder Grinding in Automobile 
Plants—Fixtures for Holding Cylinders while 
Grinding—Fixture for Airplane Engine Cylinders 
—Cylinder Grinding Attachment—Wheels for Cyl¬ 
inder Grinding. 78-106 



CYLINDER BORING, REAMING 
AND GRINDING 


CHAPTER I 

CYLINDER BORING AND REAMING 

The methods of machining the bores of various types of 
cylinders may be broadly classified as (1) boring; (2) bor¬ 
ing and reaming; (3) boring and grinding, or boring, ream¬ 
ing, and grinding; (4) boring, reaming, and lapping; (5) 
boring, reaming, and rolling or planishing. The particular 
method adopted and the type of machine used depend 
largely upon the size of the cylinder, the degree of accuracy 
necessary, and the quality of finish or smoothness of the 
surface. The quantity of the work required, or the number 
of cylinders to be bored, is also an important point to con¬ 
sider in determining the type of tool equipment, especially 
in the case of relatively small cylinders, and the design of 
the cylinder itself may affect the method of machining. 

The common method of finishing large cylinders for 
steam engines, air compressors, and other machines of this 
general class is by boring, suitable roughing and finishing 
cuts being taken with one or more single-point cutting tools. 
Cylinders of smaller size are frequently bored and then 
finished with some form of reaming tool which takes a 
very light cut to remove the tool marks left by the rough¬ 
ing cutter and, at the same time, finish the bore to a given 
diameter within close limits. Many of the small cylinders, 
however, especially of the type used on the motors of auto¬ 
mobiles, airplanes, motor boats, etc., are finished by grind¬ 
ing, after the bulk of the metal has been removed by boring 
and reaming tools. There is a decided difference of opinion 
among manufacturers as to the relative advantages of finish¬ 
ing cylinder bores by reaming as compared with grinding. 


i 



2 CYLINDER BORING AND REAMING 

When a cylinder is finished by the lapping process previ¬ 
ously mentioned, a lap or piston is inserted in it and is 
usually given a combined reciprocating and rotary motion; 
then by applying oil and a suitable abrasive the cylinder wall 
is finished. A lap without an abrasive may also be used as 
described later. The rolling or planishing process is not so 
common as the others referred to. This method, in brief, 
consists in rolling the cylinder wall by passing a cage of re¬ 
volving rollers or balls through the bore. 

Classes of Cylinder Boring Machines. The general meth¬ 
ods of boring and finishing cylinders differ in regard to the 
method of presenting the tool to the work and of obtaining 
the necessary rotating and feeding movements. For in¬ 
stance, the tool may be held stationary except for the feeding 
movement, while the cylinder is revolved, or this order may 
be reversed. In some cases, the tool is given both a rotating 
and a feeding movement, the exact arrangement depending 
upon the type or design of the machine. All cylinder boring 
machines may be included in one of three general classes 
designated as (1) machines designed exclusively for cylinder 
boring; (2) machines which may be adapted for cylinder 
boring but are intended for other operations as well; (3) 
portable machines or boring-bars which are applied to the 
cylinder to be bored. The first class includes both hori¬ 
zontal and vertical designs which vary considerably in re¬ 
gard to the general arrangement of the various details. 
The machines of this class will be referred to principally, 
variations in design being considered more in detail later. 
The second class of machines mentioned which are not de¬ 
signed primarily for cylinder boring, but which are adapt¬ 
able to it, includes such machines as engine lathes, turret 
lathes, and horizontal and vertical boring machines. The 
third class includes the various forms of portable boring- 
bars which have their own feeding mechanism and (except 
hand-operated tools for truing small cylinders) are made 
for a power drive, by belt or by a direct-connected motor. 

The cylinder boring machines of vertical design have been 
extensively used for automobile engine cylinders. These 
vertical-spindle machines differ in regard to the number of 
spindles, the mounting and driving of the spindles, the 


CYLINDER BORING AND REAMING 3 

method of obtaining the feeding movement for the cutting 
tool and in regard to the extent of automatic control. When 
two or more cylinder bores are formed in one solid casting 
or en bloc, the common practice is to use a machine having 
as many spindles as there are cylinder bores in the casting, 
so that each bore can be operated on at the same time, except 



Fig. 1. Vertical Six-spindle Cylinder Boring Machine 

when cylinders are finished by reaming, in which case 
single-spindle machines are preferred by some manufactur¬ 
ers for the final reaming operation. Some of these multiple- 
spindle machines are so constructed that the spindles may 
be adjusted along a cross-rail for varying the center-to- 
center distance, whereas on other machines the spindles are 
fixed so far as lateral adjustment is concerned. Machines 







4 CYLINDER BORING AND REAMING 

having the non-adjustable spindles are designed for exclu¬ 
sive use in a factory which requires so many cylinders that 
one or more special machines are in constant use boring 
cylinders of one size. The feeding movement of some ver¬ 
tical-spindle designs is obtained by elevating the work-table 
whereas on other machines the work-table and cylinder 
remain stationary and the spindle head is traversed along 
the vertical face of the column. These vertical-spindle 
machines used on automobile work are usually semi-auto¬ 
matic, the feed mechanism being arranged to disengage 
when the cut is completed. The return movement may also 
be controlled automatically. 

Six-spindle Cylinder Boring Machines. One of the cylinder 
boring machines used by the Continental Motors Corpora¬ 
tion is shown in Fig. 1. This is a six-spindle fixed-center 
type, which is manufactured by the Foote-Burt Co., Cleve¬ 
land, Ohio. It is shown in the illustration boring two three- 
en-bloc cylinder castings at the same time, or two castings 
each containing three bores. When the machine is in oper¬ 
ation, the table feeds upward until the boring tools have 
entered to the proper depth, when the power feed is auto¬ 
matically disengaged. A brake is provided to stop the 
spindle quickly at the end of a cut which prevents scoring 
the cylinders as the table is lowered to the starting position. 
Counterweights at the rear of the machine are connected 
with the table by means of chains which are attached at 
points directly in line with the spindles. One of these 
chains may be seen at the side of the fixture in the illustra¬ 
tion. This fixture has a removable jig-plate equipped with 
hardened and ground steel bushings. Bronze bushings on 
the spindles of the boring machine fit closely into these jig- 
plate bushings and support the spindles while the boring 
tools are at work. Two exhaust pipes connect with the base 
of the fixture and extend down beneath the machine for 
exhausting the dust. A machine of this kind which has 
fixed-center or non-adjustable spindles is adapted for plants 
producing so many motors of one size that spindle adjust¬ 
ment is not necessary. Some Foote-Burt machines are ar¬ 
ranged so that the center-to-center distance between the 
spindles can be varied if necessary- 


CYLINDER BORING AND REAMING 


5 



Fig. 2. Six-spindle Cylinder Boring Machines 






6 CYLINDER BORING AND REAMING 

The six-spindle cylinder boring machines shown in Fig. 
2 are also used by the Continental Motors Corporation. 
These machines are the product of the Moline Tool Co., 
Moline, Ill. The cylinders in this case are the six-en-bloc 
type, six bores being formed in one solid casting. The 
spindles of these machines are adjustable for varying the 
center-to-center distance, although they are rigidly tied 
together. These spindles are driven by the well-known spiral 
type of drive. The work-table feeds upward while boring, 
the feeding motion being transmitted through racks and 
pinions. The hand-operated movements of the work-table 
are controlled by the pilot wheel which the operator is hold¬ 
ing in the illustration. An adjustable stop on a vertical 
rod located just back of the pilot wheel controls the point 
at which the power feed is disengaged when the cutters have 
entered to the correct depth. This adjustable stop is en¬ 
gaged by an arm attached to the work-table. The fixtures 
on these machines have top jig-plates with bushed holes 
for guiding and steadying the spindles. The view to the 
right shows the jig-plate raised above the body of the fix¬ 
ture. Some Moline cylinder boring machines have sleeves 
which extend down to the nose of each spindle. This de¬ 
sign is used when the fixture is without a top jig-plate. 

Double-head Four-spindle Machine. The type of cylinder 
boring machine used by the Winton Motor Car Co., 
Cleveland, Ohio, is illustrated in Fig. 3. This is 
a Beaman & Smith duplex machine having two spindle 
heads and two work-holding tables mounted on a horizontal 
bed. Each head has two spindles, and when the machine 
is in use, two cylinder castings are held on each work-table. 
These castings are of the two-en-bloc design and are used 
for the six-cylinder motor. A pile of castings may be seen 
at the right in the illustration. When the machine is oper¬ 
ating, one spindle enters the bore of a casting while the 
other spindle in the same head enters the corresponding 
bore of the other casting on the same work-table. After 
one bore in each casting has been roughed out, the work¬ 
table is moved in a crosswise direction for locating the 
spindles opposite the two remaining bores. The table is 
accurately located in the two positions by a plug which 


CYLINDER BORING AND REAMING 


7 



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The cylinders are rough-bored to within about work, cylinder bores being cored to within about 
0.006 inch of the required size. This practice % inch of the final size. 













8 


CYLINDER BORING AND REAMING 

Combination Cylinder Boring and Milling Machine. The 

Beaman & Smith combination boring and milling machines 
used at the plant of the Packard Motor Car Co., Detroit, 
Mich., are so arranged that the bottoms or crankcase ends 
of the cylinder castings are face-milled, and then the castings 
are bored on the same machine and without removing them 


Fig. 4. 


Combination Cylinder Boring and Milling Machine 


from the fixture. A general view of one of these machines 
is shown in Fig. 4. The cylinders are roughed out on this 
machine and are afterward reamed and ground. Eight 
cylinder castings are held in the fixture at one time and the 
work-table is located between the boring spindles and the 
milling cutters. The boring spindles are at the left of the 
operator on this particular machine, and the milling cutters, 











CYLINDER BORING AND REAMING 9 

at the right. The saddle carrying the two milling-cutter 
spindles is mounted on a small cross-bed located at right 
angles to the main bed. The work-table is revolved one- 
quarter revolution after the two castings on one side have 
been milled, and two on the opposite side have been rough- 
bored. This indexing movement of the work-table locates 
two rough castings in front of the milling cutters and two 
which have been face-milled, in front of the boring spindles. 
The work-table is provided with a ball bearing which is 
raised by a handwheel and takes the weight of the table, 
so that it can be revolved or indexed easily. The work¬ 
table, however, does not rest upon this ball bearing when 
the machine is at work milling and boring, but on a straight 
surface of large diameter. The table is accurately located 
in any one of its four positions by a locking pin which 
enters one of four holes, and it can be securely fastened after 
being located by this pin. The spindle head moves along 
the bed to provide the feeding movement for boring, and 
it has a rapid traversing movement. The saddle carrying 
the milling cutters also has a rapid power traverse. 

Another boring and milling machine used for the six-en- 
bloc cylinders is illustrated in Fig. 5. This machine has the 
same general features as the older design previously de¬ 
scribed, except that there are twelve spindles on the boring 
side instead of six. These spindles are located at the right- 
hand end of the machine as shown in the illustration. The 
fixture is arranged to carry eight six-en-bloc castings. The 
roller platform or track seen in the foreground is used 
to convey the cylinders from one machine to another. The 
two pipes located just above each group of boring spindles 
are for exhausting the dust. In operating a machine of this 
type, the principal work is to remove the bored castings and 
insert rough ones in the fixture. After the rough castings 
are placed in the fixture, the indexing movement of the 
work-table locates the castings in front of the milling cut¬ 
ters, where the crankcase ends or faces are milled before 
the boring operation. The cylinders are rough-bored to 
within 0.100 inch of size on this machine, and then they are 
reamed prior to grinding on a multiple-spindle vertical 
machine. 


10 


CYLINDER BORING AND REAMING 



Fig. 5. Another Combination Cylinder Boring and Milling Machine 









CYLINDER BORING AND REAMING H 

Twelve-spindle Cylinder Boring Machine. The twelve- 
spindle Beaman & Smith machine used for reaming Pack¬ 
ard cylinders prior to grinding is illustrated in Fig. 6. The 
two groups of six spindles each are located in planes at 
right angles to each other, so that the loading and unloading 
positions of the fixture or work-table are at adjacent sides 


Fig, 6. Twelve-spindle Vertical Cylinder Boring Machine 



instead of being at the front and rear. This machine is 
designed, of course, to ream two cylinder castings or twelve 
cylinder bores simultaneously. The machine is semi-auto¬ 
matic in its operation, the downward feed of the spindle 
slides being automatically disengaged when the cutters have 
reached the desired depth. The cutter-bars are driven 










12 CYLINDER BORING AND REAMING 

through floating connections and the bars are guided and 
steadied by bronze bushings which enter the upper ends 
of the cylinder bores. Each group of three spindles is pro¬ 
vided with a presser-foot which is free to move upward 
against the compression of a spiral spring that surrounds 
the upper end of the presser-foot rod. As the cutter-bars 
descend, each presser-foot automatically forces three guide 
bushings down into holes in the top of the fixture. When 
the cutter-bars are removed at the completion of the reaming 
operation, the bushings are carried up with the spindles so 
that the operator does not have to bother with this feature. 
Each casting is located in the fixture by two pins which 
engage holes near the ends. The finished face of the casting 
is forced upward against the top of the fixture by clamps 
below the casting. 

Rough- and Finish-boring on a Single-spindle Machine. 
At the plant of the H. H. Franklin Mfg. Co., Syracuse, 

N. Y., the cylinders are bored prior to grinding on Baker 
single-spindle machines. One of these machines equipped 
for cylinder boring is shown in Fig. 7. Each casting has a 
single bore, and, before the boring operation, the cylinder 
flange is rough-faced on a vertical boring mill. Roughing 
and finishing cuts are also taken in the bore itself to a 
depth of % inch. This part of the bore is finished to the 
size of a locating plug corresponding to plug A in the il¬ 
lustration. This plug is 1/16 inch smaller in diameter than 
the final size. The end of the bore is also chamfered during 
this preliminary operation. The cylinder is now ready for 
the machine shown in Fig. 7. It is located in the fixture by 
plug A which is inserted in a bushing in the fixture and 
engages the part of the bore previously machined. The 
cylinder is clamped against the top of the fixture by four 
clamp bolts and four screws and it is further secured by a 
screw at the bottom of the fixture which bears against the 
cylinder head. The roughing cutter has six blades or cut¬ 
ters, and it leaves from 0.060 to 0.070 inch in the bore. The 
head or end of the cylinder is next rough-faced with a 
double-blade tool, after which a second cut is taken through 
the bore with a six-blade tool which leaves from 0.013 to 

O. 015 inch for the final grinding operation. The casting 




CYLINDER BORING AND REAMING 


13 


is not removed from the fixture until it is finished, ready 
for grinding. The machine has a special spindle with a 
screw at the end which enables the cutters to be changed 
rapidly. The output of one machine usually varies from 
seven to eight castings per hour. The single-spindle machine 
has proved satisfactory for this work on the cylinders. 

Finish-reaming on a Single-spindle Machine. Some auto¬ 
mobile and gas engine manufacturers who finish cylinder 



Fig. 7. Rough- and Finish-boring on Single-spindle Machine 

bores by reaming, prefer to use a single-spindle machine 
for the final reaming operation in preference to a multiple- 
spindle machine. One object of using a single-spindle 
machine instead of a multiple type is to obtain greater 
uniformity in the diameter of different bores by finishing 
each bore with the same reamer. Fig. 8 illustrates how 
cylinders are reamed on a single-spindle Colburn drilling 
machine at the plant of the H. J. Walker Co., Cleveland, 





14 CYLINDER BORING AND REAMING 

Ohio. These three-en-bloc cylinders are for Chandler cars, 
and the bore is 3l/ 2 inches in diameter and 9 inches long. 
Forty of these castings, or 120 cylinder bores, are reamed 
in nine and one-half hours. 

The cylinders are first rough-bored on a double-column, 


Fig. 8. Reaming Multiple Cylinders on a Single-spindle Machine 

twelve-spindle Beaman & Smith machine of vertical design, 
and then they are reamed. The fixture for this reaming 
operation is provided with a suitable indexing device for 
locating each of the three bores in the reaming position. 
This indexing movement is controlled by a plunger which 
engages three equally spaced holes in the fixture slide. The 




CYLINDER BORING AND REAMING 15 

hand-lever for operating this plunger may be seen at the 
front of the fixture. The casting is held against the upper 
part or bridge of the fixture by means of pneumatically- 
operated clamps. Each clamp is pivoted near the top of the 
fixture and the outer end is attached to the pneumatically- 
operated piston or plunger. When the air pressure is re¬ 
leased, the clamps are withdrawn from the casting by means 
of spiral springs so that they do not interfere with re¬ 
moving the finished casting or inserting a rough one. 

Multiple reaming was superseded by the single-spindle 
method of reaming, because it was considered practically 
impossible to finish all the bores in any one casting to the 
same size without using the same reamer in each bore. 
Another disadvantage mentioned in connection with multiple 
reaming is that if one reamer does not cut properly, the en¬ 
tire machine must stand idle while a new reamer is being 
fitted and tried. The experience has been that a new 
reamer usually has to be stoned a little after trial to make 
it cut smoothly. On the contrary, if two or more single- 
spindle machines are used for reaming, when a reamer does 
not cut properly, only one machine is affected. 

Heating Reamers to Avoid Errors Due to Expansion. The 
practice of the Ferro Machine & Foundry Co., Cleveland, 
Ohio, in machining cylinder bores varies somewhat accord¬ 
ing to the specifications of the customer. Some cylinder 
bores are finished by reaming and others by grinding. 
When cylinders are finished by reaming, the reamers are 
heated, before using, to approximately the temperature to 
which a cold reamer would be heated as the result of the 
reaming operation. The object of this preliminary heating 
is to bring the reamer up to the working temperature when 
the operation is first started, thus avoiding errors resulting 
from expansion. 

Fig. 9 shows two of the boring machines used in this 
plant. If the cylinders are to be finished by reaming, either 
three or four cuts may be taken, depending upon conditions. 
When there are three cuts, a four-blade tool is used for 
roughing; a six-blade tool, for the semi-finishing cut; and 
a twelve-blade floating reamer for finishing. The feed for 


10 CYLINDER BORING AND REAMING 

the heavy roughing cut is 1/32 inch; for the semi-finishing 
cut, Vs inch; for the reaming operation, 3/64 inch. The 
cylinder bore is enlarged about % inch by the semi-finishing 
cut and 0.020 inch by the reamer. If the cylinder bores are 
rather long or the ends of the cylinders closed, two semi¬ 
finishing cuts may be taken to insure getting the bore square 
with the face or flange. The cylinders shown in Fig. 9 
have bores 4 inches in diameter and 9 inches deep, and 



Fig. 9. Four-spindle Cylinder Boring Machines 


about sixty of these four-cylinder castings are bored in ten 
hours. 

Speeds and Feeds for Reaming. The Gisholt Machine Co. 
recommends a cutting speed for reaming equal to about 
one-third or one-half the highest cutting speed for rough¬ 
boring ; thus, if the speed for roughing is 40 feet per minute, 
the approximate reamer speed would be from 15 to 20 feet 
per minute. When reaming cylinders or other work re¬ 
quiring a very good finish, the speed might be reduced. A 
feed of about % inch per revolution is recommended for 
reaming cylinders. The feed for reaming steel varies con¬ 
siderably more than for cast iron, owing to the difference 













CYLINDER BORING AND REAMING 17 

in hardness. Soft steel requires a finer feed than steel 
having a higher carbon content. The feeds for reaming 
steel usually vary from about 0.040 to 0.125 inch. For 
reaming steel, the reamer should be flooded with lard oil 
or some cutting compound. 

The speeds and feeds recommended by the National Tool 
Co., Cleveland, Ohio, for reaming cast-iron cylinders with 
the reamers of this company are as follows: When two 
roughing reamers are used, the first one should operate at 
a speed of 38 feet per minute, with a feed of 1/16 inch per 
revolution, using soda water. The cylinders should be placed 
in an oven or furnace to dry them thoroughly, before using 
the semi-finishing or the floating finishing reamer, assum¬ 
ing that soda water is used for the roughing cut. The semi¬ 
finishing or second roughing reamer should have a speed of 
32 feet per minute, and a feed of l/g inch per revolution. 
This reamer should remove 0.060 inch of stock and the cut 
should be taken perfectly dry. The speed recommended for 
the floating finishing reamer is 27 feet per minute and the 
feed 3/32 inch per revolution. This cut is also taken per¬ 
fectly dry and tests have shown that the best allowance for 
finishing with the reamer referred to is 0.010 inch. 

Heat-treatment after Rough-boring. It is the practice of 
some automobile and other manufacturers of gasoline en¬ 
gines to subject cylinders to heat-treatment for relieving the 
internal stresses in the casting. The heat-treating process 
follows the rough-boring operation, although it is not always 
the next successive operation. The practice of the White 
Co., where cylinders are finished by boring, reaming, and 
grinding, is first to bore and ream the castings, and then 
heat them to 500 degrees F., for a period of four hours. 
The intention is to heat the casting before the final grinding 
operation to as high a temperature as it will be subjected to 
in practice. The cylinders are then ground after any 
changes have occurred which might result from the internal 
stresses that are released during the heating period. 

At the Studebaker plant, castings are heat-treated as soon 
as they are rough-bored. Gas-fired furnaces are used, and 
the temperature is raised to 575 degrees F. This heat- 
treating process requires about forty minutes. The cast- 




Machinery 






























































































































































































































































































































































































































CYLINDER BORING AND REAMING 19 

ings are then removed from the furnace and allowed to 
cool in the atmosphere. After any existing stresses have 
been relieved, the other machining operations on the bore 
are completed. 

Scleroscope Test before Boring. It is the practice of the 
Reo Motor Car Co., Lansing, Mich., to test the hardness of 
cylinder castings before boring, by using a scleroscope. The 
scleroscope test is applied to a certain percentage of the 
castings in each shipment, and if many hard castings are 
found, the test is applied to the entire lot. The average 
run of castings have a hardness of between 30 and 40 on the 
scleroscope scale. The relatively hard castings are grouped 
together and machined separately, because it has been 
found that uniformity in the castings enables them to be 
machined to better advantage. 

Machine for Lapping Cylinders. The standard practice in 
finishing the cylinders of Studebaker motors is by lapping 
on a special machine designed for this purpose. The machin¬ 
ing operations on the cylinder bore include (1) a rough¬ 
boring cut; (2) a lighter roughing or semi-finishing cut; 
(3) finish-reaming; and (4) lapping. The lapping machine 
is provided with six spindles which serve to lap the six 
cylinder bores simultaneously. The general type of machine 
used is illustrated in Fig. 10, which shows the four-spindle 
design. The lapping spindles and laps L are given a com¬ 
bined reciprocating and rotating motion. The reciprocating 
movement is derived from a crankshaft A at the top of the 
machine. The lapping spindles connect with this shaft by 
means of Scotch yokes B. The rotary motion is reversing, 
the laps being turned about one-half revolution in first one 
direction and then the other. This reversing rotary move¬ 
ment is derived from a crank C which transmits motion 
through a Scotch yoke connection and horizontal rack, mesh¬ 
ing with pinions which are splined to the lapping spindles. 
The main driving shaft extends along the rear of the 
machine at D. This shaft drives the main crankshaft A 
through shaft E and the bevel gearing shown. The casting 
to be lapped is placed within work-table F which is enclosed 
at the sides to form a reservoir for the kerosene used in 
connection with the lapping operation. This work-table 


20 CYLINDER BORING AND REAMING 

may be raised and lowered upon the vertical face of the 
machine column and it is attached to a counter-weight G. 
Each spindle has attached to its lower end a cast-iron lap. 
No abrasive whatever is used, the lap simply being trav¬ 
ersed through the cylinder bore which is continually flooded 
with kerosene. A detail view of one of these laps is shown 
in Fig. 11. The lapping surface is formed of four cast-iron 
segments L. These segments are free to expand, being 
forced outward against the cylinder wall by a spring S 
which exerts a pressure of about 30 pounds. These laps are 
traversed through the cylinder bores at the rate of about 
480 strokes per minute, and from twelve to twenty minutes 
is required for lapping a cylinder casting. 



Fig. 11. Design of Lap used in Connection with Machine 
shown in Fig. 10. 


Finishing Bores by Rolling or Planishing. The rolling or 
planishing method of finishing cylinder bores consists in 
feeding down through the bore a cage of hardened rollers or 
balls which enlarge the bore slightly, thus sizing it and at 
the same time producing a hard, dense wearing surface. 
This method has been used by only a few manufacturers, 
although when properly applied it seems to be entirely 
satisfactory; in fact, the cylinders of Ford cars are finished 
in this way. The hardened steel rollers are mounted in a 
cage so that they are free to turn and are located parallel 
with the axis of the cylinder. These rolls are not exactly 
cylindrical but are ground with a slight curvature, the 
diameter in the center being about 0.001 inch larger than 
at the ends. There are approximately twenty of these roll- 





























CYLINDER BORING AND REAMING 21 

ers, and as the cage, which is attached to the machine spin¬ 
dle, feeds downward, the rollers compress the metal and 
slightly enlarge the bore to the finished size. The cage of 
rollers should be oiled freely while it is passing through the 
cylinder. Formerly, this work was done on a single-spindle 
drilling machine, but now a four-spindle machine is used 
for rolling the four bores at the same time. Prior to this 
rolling process, the cylinders are carefully reamed to give 
the necessary allowance for rolling. This general method 
of finishing cylinders has also been used for finishing the 
bores of some motorcycle cylinders. 

Rolling Process for Motorcycle Cylinders. The cylinders of 
Henderson motorcycles, manufactured by the Excelsior 
Motor Mfg. & Supply Co., Chicago, Ill., were formerly fin¬ 
ished by the rolling or planishing process. After two years’ 
experience with the rolling of cylinder bores, this method 
has been replaced by grinding to obtain the final finish. 
The following report of the Engineering Department ex¬ 
plains why the rolling process was discontinued, and in¬ 
cludes some important data and information pertaining to 
the rolling method of finishing motorcycle cylinders: 

“While the rolling process is an improvement over ream¬ 
ing, it is not as dependable as grinding. The rolling smooths 
and hardens the surface and reduces friction a great deal, 
but the cylinder is still a reamed job and subject to the 
defects caused by reamer troubles. If the reamer could 
be made to ream a perfect bore continuously, reamed and 
rolled cylinders would prove to be even superior to ground 
cylinders. When the Henderson cylinders were rolled, they 
were finish-reamed in a vertical position with a Kelly 
reamer. The bore was 2% inches in diameter. The cylin¬ 
ders were reamed to 2.6245 inches, allowing only 0.0005 inch 
for rolling, as not more than 0.00025 inch of metal could be 
rolled down on a side. The outside diameter of the roller 
cage was 2.6265 inches, indicating that the cylinder was 
sprung open 0.002 inch by the pressure of the rolls and back 
to size when released. On account of this pressure, the 
process could not be used on all cylinder designs. The Hen¬ 
derson cylinder design was all right on account of the even 
distribution of air-cooling flanges. The construction of the 


22 CYLINDER BORING AND REAMING 

cage of rollers is similar to that of a regulation roller bear¬ 
ing. For rolling a 2%-inch cylinder, a cage of eight rollers 
was used. The rollers were % inch in diameter and 1 inch 
long. A ball bearing should be used above the cage to take 
the thrust. Th& cage should be made as strong as possible, as 
the twisting strain on the rollers is severe. The rollers need 
not have much “lead” or curvature, a slight radius at the 
ends being sufficient. The rolling should be done at about 
the same feed and speed as for reaming. The cost of rolling 
a cylinder bore is much less than grinding, the production 
being fully three times as fast.” 

Tool for Cylinder Rolling. While the cylinders of Stude- 
baker motors are finished on a lapping machine, as previ- 



Fig. 12. Rolling Tool used for finishing Cylinder Bores 
by the Rolling or Planishing Process 


ously described, the rolling process is applied under certain 
special conditions. The interesting design of rolling tool 
used is illustrated in Fig. 12. This tool has eighteen hard¬ 
ened steel rollers A. The central part of these rollers, 
which comes into contact with the cylinder bore, is % inch 
in diameter. The rollers are tapering at each end and 
beyond the tapering part there is a cylindrical bearing 
which engages the retainers B and C. The rollers are not 
located parallel with the axis of the tool, but are set at an 
angle of 1 % degrees, so that the tool readily feeds itself 
through the cylinder bore. As the illustration shows, the 
rollers are so inclined that the leading ends are slightly 
back of the following ends, which causes the tool to advance 

































CYLINDER BORING AND REAMING 


23 


through the cylinder bore. The rate of feed is about Yb 
inch per revolution. The diameter over the rollers is 
approximately 0.001 inch larger than the finished diameter 
of the bore to be rolled. When the tool is in use, the rollers 
bear between the wall of the cylinder and a hardened and 
ground collar, which is free to revolve about a bushing 
attached to a central stem on the holder. Washers E and F 
are placed on each side of the cage of rollers, and a nut G 
is screwed on the end of the holder to keep the parts in 
position. This tool is used on a drilling machine having a 



Fig. 13. Horizontal Boring Machine equipped with Special 
Attachment for boring Radial Cylinders 

tapping attachment, so that the spindle may be reversed for 
backing the tool out of the cylinder bore. The wall of the 
cylinder springs slightly when being rolled. For instance, 
if the cylinder is 0.003 inch under size, it will not be en¬ 
larged exactly 0.003 inch by the rolling tool, but a little 
less, because the cylinder wall springs back slightly after 
the rolling operation. 

Radial Cylinder Boring Attachment. A very unusual cyl¬ 
inder boring operation and the special attachment required 
for it are shown in Fig. 13. The cylinders bored by using 
this attachment in conjunction with a horizontal boring, 











24 


CYLINDER BORING AND REAMING 


drilling, and milling machine are curved sections which 
form part of a pneumatic carrier system. Each section 
of the curved portion of the pneumatic tube had to be 
bored to a radius of 8 feet. The diameter of each section 



Fig. 14. Boring a 78-inch Cylinder on a Vertical Boring Mill 

is about 8% inches and the length, approximately 2 feet. 
The attachment is arranged to swing the cylinder casting 
about a radius of 8 feet as the machine table travels length¬ 
wise along the bed. In order to obtain this swinging move¬ 
ment, two arms which are attached to the work-holding 











CYLINDER BORING AND REAMING 


25 


fixture are pivoted to a stationary pin located at a point 
farther to the left than is shown in the illustration. This 
radius boring attachment operates on the same general 
principle as some of the attachments used in locomotive 
shops for planing and also for grinding the links of the 
valve operating mechanism. 

Boring Large Cylinders. Very large cylinders are usually 
bored on either vertical or horizontal boring machines of 
the general type designed for various other classes of work. 
If the length of the bore is rather long as compared with 
the diameter, it may be necessary to use a horizontal ma¬ 
chine, but if the length of the bore is not excessive, the ver¬ 
tical type is often employed. As a general rule, very large 
cylinders, while being bored, should preferably be in the po¬ 
sition they will occupy when assembled and in use. For in¬ 
stance, a very large low-pressure cylinder for a vertical 
marine engine should be bored while in a vertical position, 
because if the horizontal boring machine is used, the cyl¬ 
inder is likely to spring slightly to an oval shape while being 
bored, so that it will not be true after it is finished and 
placed in a vertical position. 

Fig. 14 shows an example of large cylinder boring on a 
vertical boring mill. This is a 78-inch low-pressure cylinder 
for a rolling mill engine, and it weighs 84,000 pounds. This 
is an example of the heavy cylinder work done at the West 
Allis Works of the Allis-Chalmers Mfg. Co., Milwaukee, Wis. 
Another very large cylinder is shown in Fig. 15. This is an 
84-inch low-pressure steam cylinder, and the length of the 
bore is 60 inches. The vertical boring mill used for this 
work is a 20-foot size. This cylinder is intended for a hori¬ 
zontal cross-compound blowing engine built by the Mesta 
Machine Co., Pittsburg, Pa. 

When setting a cylinder casting, if the design will per¬ 
mit, it should be set true by the outside of the flange or, 
better still, by the outside of the cylinder body, so that the 
walls of the finished cylinder will be of uniform thickness. 
The finishing cut should also be a continuous one, because 
it the machine is stopped even for a short time, the tool 
cools somewhat, and as the result of contraction a ridge is 


26 CYLINDER BORING AND REAMING 

left in the bore. This is one reason why an independent 
drive is preferable for a boring machine, especially if the 
latter is used on large work which requires in some cases 
considerable time for taking a cut through the bore. . A 
horizontal machine is shown in Fig. 16 boring and facing 



Fig. 15. Boring an 84-inch Cylinder on a Vertical Boring Mill 


the casing of a steam turbine at the plant of the Westing- 
house Electric & Mfg. Co., East Pittsburg, Pa. 

Machine for Corliss Engine Cylinders. Steam engine cylin¬ 
ders of the Corliss or four-valve type are often bored on a 
special type of machine having three boring-bars which may 
operate at the same time. One of these machines built by 
the Niles Works of the Niles-Bement-Pond Co., and installed 
at the plant of the Allis-Chalmers Mfg. Co., Milwaukee, 



CYLINDER BORING AND REAMING 


27 



Fig. 16. Boring and facing the Casing of a Steam Turbine 









28 


CYLINDER BORING AND REAMING 



Fig. 17. Horizontal Boring Machine designed especially for Engine Cylinders of the Corliss Type 






























CYLINDER BORING AND REAMING 29 

Wis., is illustrated in Fig. 17. The port boring attachment 
consists of two vertical columns which may be adjusted 
along the bed parallel to the main boring-bar. On the face 
of the larger column there are two saddles, each of which 
carries a port boring-bar which is additionally supported by 
a bearing on the other column, as the illustration shows. 
These saddles and auxiliary boring-bars are adjusted ac¬ 
cording to the center-to-center distance between the valve 
ports. The machine shown in Fig. 17 also has two heavy 
facing arms for facing the cylinder flanges at the ends of 
the cylinder. Each arm is provided with a tool-block or tool- 
slide and a feed-screw which is turned one-sixth revolution 
each time the main boring-bar makes a complete revolution. 
This feeding movement is derived from the well-known 
star feeding mechanism, there being a star-wheel attached 
to the end of the feed-screw which strikes a fixed pin. 

Grinding Single-point Cylinder Boring Tools. When single¬ 
point tools are used for taking the finishing cuts in cylin¬ 
der bores, especially of the larger sizes, there are two 
general methods of grinding them. Some contend that a 
tool which has a rather narrow rounded point gives better 
results than one having a broad flat cutting edge. When a 
narrow tool is used, the feed is, of course, reduced accord¬ 
ingly, and it is claimed that greater accuracy is obtained 
because the tool is not deflected as much as one having a 
broader cutting edge when it encounters hard spots in the 
casting. The narrow ridges which may be left by a narrow 
tool are also regarded as an advantage by some mechanics, 
the contention being that they form minute pockets for 
oil and facilitate lubrication. If the boring machine, how¬ 
ever, is sufficiently rigid to permit using a rather broad 
tool and a coarse feed for the finishing cut, the time for 
taking this cut can be greatly reduced and there is less 
wear on the tool since the work is done in less time. The 
massive boring-bars found on modern machines will not be 
deflected appreciably when a broad tool is used. When 
using some machines, it is necessary to reduce the width of 
the cutting edge in order to prevent chattering. 

Cylinder Boring in Engine Lathes. Ordinary engine lathes 
are sometimes used for cylinder boring when a horizontal 


30 CYLINDER BORING AND REAMING 

boring machine or some other type of tool better suited to 
such work is not available.- If the cylinder casting is too 
large to be gripped in a chuck or bolted to the faceplate, 
it is clamped to the lathe carriage. One method is to place 
a boring-bar between the centers, which has one or more 
cutters centrally located and rigidly secured to it. As the 
boring-bar is revolved, the feeding movement is obtained by 
traversing the carriage along the bed with the regular powei 
feed. In this case, the boring-bar must be about twice as 
long as the cylinder to provide room for the necessary feed- 



Fig. 18. Boring a Locomotive Cylinder Lining in an Engine 
Lathe equipped with a Boring-bar 

ing movement. Another type of boring-bar for use in the 
lathe is illustrated in Fig. 18, which shows how the lining of 
a locomotive cylinder is bored. The cutter-head in this 
case is traversed along the bar itself by a star feed mechan¬ 
ism and a lead-screw inserted in a groove extending along 
one side of the boring-bar. A disk or plate is attached to 
the tailstock spindle and carries a pin which strikes the 
star-wheel each time the boring-bar makes a revolution. 
The star-wheel is thus turned one-fifth revolution and this 
rotary movement is transmitted by means of spur gears to 
the lead-screw, which, in turn, actuates the cutter-head. 




CYLINDER BORING AND REAMING 


31 


Incidentally, the outside of this cast-iron lining is rough- 
turned before boring, in order to avoid the distortion which 
might occur if this hard outer surface were removed after 
boring. Special fixtures are sometimes provided for holding 
linings or cylinder castings to the lathe carriage to facilitate 
clamping and adjusting the work. When a cylinder lining 
or similar part must be bored in the lathe, if no fixture has 
been provided, wooden blocks clamped across the wings of 
the carriage at each end will serve the purpose. Circular 
seats having a radius equal to the outer radius of the lining 
may be cut into these blocks by using a special hook-shaped 



Fig. 19. Engine Lathe arranged for boring Cylinders of 
Airplane Motors 


cutter attached to the boring-bar. The cutter is set to the 
required radius and it should revolve rapidly for this oper¬ 
ation. 

Boring Cylinders of Airplane Motors in Engine Lathes. 

Fig. 19 shows how an ordinary engine lathe is used by the 
Curtiss Aeroplane & Motor Corporation, Hammondsport, N. 
Y., for boring airplane motor cylinders. The cylinders are 
first rough-bored in a Jones & Lamson flat turret lathe, a 
special fixture being used to hold them in position. A 
double-ended boring tool mounted on a very heavy arbor at¬ 
tached to the turret is used for this preliminary boring oper- 





32 CYLINDER BORING AND REAMING 

ation. The second boring operation is performed on an 
engine lathe, as shown in Fig. 19. This lathe is equipped 
with a special work-holding fixture attached to the spindle 
and a very stiff single-ended boring tool is used. This method 
has been adopted to insure absolute alignment of the bore 
relative to the clamping flange. The cylinder is finally fin- 



Fig. 20. Portable Boring-bars reboring the Worn Cylinders 
of a Locomotive 


ished by grinding on a Heald cylinder grinder within a limit 
of 0.001 inch plus or minus from the standard diameter. 

Portable Boring-bars for Cylinder Work. Portable boring- 
bars are often used for boring or reboring cylinders which 
are too large to be placed on a fixed machine or which 
should preferably be bored while assembled. In locomotive 





CYLINDER BORING AND REAMING 


33 


repair shops portable boring-bars are used for reboring 
cylinders which have become worn by the reciprocating mo¬ 
tion of pistons. These pistons, which bear principally on 
the bottom of the cylinder, wear the latter out of round and 
also form shoulders at each end of the stroke. The general 
type of boring-bar used for truing worn cylinders is illus¬ 
trated in Fig. 20, which shows two boring-bars operating 
at the same time on the cylinders of a dismantled locomo¬ 
tive. One of these boring-bars is boring a low-pressure 
cylinder and the other the high-pressure cylinder of the 
opposite side. The bar itself is carried by brackets attached 
to the front and rear ends of the cylinder. Power for 
driving the bar may be obtained from a portable electric 
motor connected by a belt, or a pneumatic motor of the type 
used for drilling may be applied directly to the shaft of the 
driving pinion. A handwheel is sometimes attached to the 
driving shaft when power is not available. As the illustra¬ 
tion shows, motion is transmitted to the bar through a train 
of spur gearing. The cutter-head is traversed along the bar 
by a lead-screw which is placed in a groove or channel ex¬ 
tending along one side, so that it is below the surface of the 
bar. The feeding movement of the boring-bar shown in Fig. 
20 (manufactured by H. B. Underwood & Co., Philadelphia, 
Pa.) is obtained through planetary gearing. Two changes 
of feed are provided and the power feed may readily be 
disengaged. When setting up one of these portable boring 
bars, it is centrally located with reference to the cylinder 
counter-bores at each end, because they have not been 
subjected to wear and are concentric with the original bore. 
After a cylinder has been bored out repeatedly and the 
diameter is increased considerably, the original size is ob¬ 
tained by inserting a lining. 


CHAPTER II 


CYLINDER BORING AND REAMING TOOLS 

The boring and reaming tools used by different manufac¬ 
turers for roughing and finishing the cylinders of automo¬ 
bile engines and other comparatively small cylinders differ 
considerably both in regard to their design and in the 
method of applying the tools. The variations in practice 
are due, in part, to the fact that some manufacturers prefer 
to finish the cylinder bores by a cutting or reaming tool, 
whereas others prefer to obtain the final finish by grinding. 
Aside from the type or design of tool used, the practice 
varies in the number of cuts which are considered necessary 
either for completely finishing cylinder bores or for ma¬ 
chining them close enough to the required size for a final 
grinding operation. As the results obtained in connection 
with boring and reaming practice may depend largely upon 
the cutting tools used, various designs which have been em¬ 
ployed successfully will be described. 

In referring to the designs illustrated, it will be noted 
that they differ principally in regard to the number of cut¬ 
ting blades, the position of the blades and the method of 
holding and adjusting them. The number of blades on tools 
of this class ordinarily varies from two to eight, although 
some finishing reamers have twelve blades. In some plants 
two-bladed tools are used for both roughing and finishing, 
whereas in others a finishing reamer having at least from 
four to six blades is considered preferable for both roughing 
and finishing cuts. The finishing reamer usually has a float¬ 
ing movement, although some manufacturers contend that 
better results are obtained by using a rigid or fixed tool for 
both the roughing and finishing cuts. The different types 
of tools to be described will serve to illustrate some of the 
more important variations in practice as applied to boring 
and reaming tools for cylinder work. 


34 


CYLINDER BORING AND REAMING TOOLS 



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35 


semi-finishing cuts, and then the bore is finished firmly in place. This construction is considered 
by grinding. The roughing cutter has six blades better than using a flattened taper pin which 
which are set at an angle of 10 degrees with the bears directly against the side of the cutter. With 
axis and at an angle of 3 degrees from a radial the method illustrated in Fig. 1, each cutter blade 
position, to provide rake. The cutter blades are, has a full bearing on both sides and is held 



































36 CYLINDER BORING AND REAMING TOOLS 

more securely than when one side bears against a pin. 
The end of the cutter body is bored out to a diameter of 
1% inches, and to a depth of 1 inch to secure greater flex¬ 
ibility for the sections which are expanded by the taper 
pins. A tool-steel block A is inserted in this hole to provide 
a backing or support for the cutter blades. This block is 
held in position by a %-inch fillister-head screw. The cutter 
blades have a land 1/32 inch wide. 

The tongue at the base of the shank for driving the cutter 
has radial driving surfaces at B and C. The object of locat¬ 
ing the driving surfaces in a radial position is to change the 
direction of the thrust on the slotted end of the machine 
spindle. When the driving faces are radial, there is less 
tendency for the slotted end of the spindle (which receives 



Fig. 2. Another Design of Six-blade Roughing Cutter 


the tongue) to spread when subjected to heavy stresses, be¬ 
cause the thrust is more nearly in line with the solid section 
of the spindle. The semi-finishing cutters are practically 
the same as the type used for roughing, except that the 
blades are held parallel with the axis instead of being in¬ 
clined. 

The Continental Motors Corporation, Detroit, Mich., uses 
three boring or reaming tools, but the cylinders are finally 
finished by grinding, as this is considered the only prac¬ 
ticable method of securing the desired accuracy in quantity 
production. The tool illustrated in Fig. 2 is used for the 
first and second rough-boring operations. There are six 
blades or cutters, and these are located at an angle of 10 
degrees to give the required rake. The finishing reamer 
















CYLINDER BORING AND REAMING TOOLS 


37 


which follows the two roughing cuts leaves the bore from 
0.006 to 0.008 inch under size for grinding. These tools are 
provided with a tongue 1% inches wide just back of the cut¬ 
ter body, which engages a slot in the machine spindle and 
provides a positive drive. The cutters are held in place by 
pins flattened on one side to an angle of 3 degrees. 

Two-blade Tool for Straightening Bore. Two designs of 
cylinder reamers used by the Rutenber Motor Co., Marion, 
Ind., are shown in Fig. 3. The cylinders are first rough- 



bored with a six-blade tool of the type shown at A. This 
tool is followed by the two-blade design illustrated at B, 
and then another six-blade tool is used and the cylinders 
are finally finished by grinding. The object of using the 
two-blade tool is to straighten the bore. If the tool used 
for the first roughing cut is deflected laterally owing to une¬ 
qual distribution of the metal in the cored hole, it is claimed 
that the two-blade tool will straighten the bore, because it 
is less likely to be deflected and tends to finish the bore more 
nearly in alignment with the machine spindle. The six- 

































38 CYLINDER BORING AND REAMING TOOLS 

blade tool is then used prior to grinding, the claim being 
that it finishes the hole more smoothly than a two-blade tool 
and also produces a perfectly round hole, thus making it 
possible to finish the bore close to the grinding size. The 
blades of the tools illustrated in Fig. 3 are set at an angle 
of 7 degrees; and they are held in position by 5/16-inch 
pins flattened on the side. The center line of the taper pins 



Fig. 4. Four-blade Rougher and Eight-blade Reamer for 
machining Cylinders before grinding 


makes an angle of 9 degrees with the axis of the reamer. 
The bottoms of the slots for the blades are milled to an angle 
of 3 degrees to provide for radial adjustment. The diam¬ 
eter of the first roughing tool is 3 inches. The hole is then 
enlarged to 3.070 inches by the two-blade tool, after which 
it is further enlarged to 3.114 inches by the final boring tool, 
the last operation bringing it to within 0.011 inch of the 
finished size, which is 3.125 inches. 





CYLINDER BORING AND REAMING TOOLS 39 

Four-blade Roughing Tool Followed by Eight-blade 
Reamer. The types of tools used by the White Co., Cleve¬ 
land, Ohio, for machining cylinder bores prior to grinding 
are illustrated in Fig. 4. For rough-boring, the four-blade 
boring tool seen in the upper part of the illustration is used. 
After a number of cylinders have been bored, the first 
roughing cutters are replaced by eight-blade reamers of the 



Fig. 5. (A) Roughing Cutter. (B) Eight-blade Tool used 

before Grinding Operation 


design shown in the lower part of the illustration. The cylin¬ 
ders are then reamed on the same machine prior to grinding. 

Six-blade Roughing Tool Followed by Eight-blade 
Reamer. At the plant of the Reo Motor Car Co., Lansing, 
Mich., the cylinders are rough-bored and reamed and are 
then finished by grinding. The first rough-boring tool is 
followed by a second roughing tool and then a light cut is 
taken by a third tool prior to grinding. The tool used 
for the first rough-boring operation is shown at A, Fig. 5. 
This tool has six high-speed steel blades, and each blade is 
































































40 


CYLINDER BORING AND REAMING TOOLS 





* 


held in place by three machine screws, the heads extension of the arbor, and is held in place by a 
of which engage shoulders formed on the side washer and countersunk screw. A %-inch slot 
of the blade. The cutter-head is mounted upon an on each side of the cutter-head at the rear en- 


















































































CYLINDER BORING AND REAMING TOOLS 41 

gages a key. These two keys are fitted to %-inch slots in 
the arbor flange, and each key is held in place by two screws. 
The keys project beyond the flange far enough to form a 
tongue for engaging a cross-slot in the machine spindle. The 
shank of the arbor is a No. 5 Morse taper. The tool used 
for the second roughing cut is practically the same as the 
one just described, except that it is a little larger in diam¬ 
eter. The eight-blade tool B finally used before grinding is 
also similar in construction to the other tools as far as the 
method of holding the cutter blades and the arrangement of 
the driving keys is concerned. This tool, which is used for 
the final reaming operation, is held rigidly to the arbor in¬ 
stead of giving it a slight floating movement, which is com¬ 
monly done with reamers used to finish cylinder bores with¬ 
out a grinding operation. Tool A rough-bores the cylinder 
to 4.658 inches; the second rough-boring tool enlarges the 
bore to about 4.708 inches; and the third tool removes 0.030 
inch, leaving the bore approximately 4.738 inches or within 
0.012 inch of the required size. 

Adjustable Rough-boring Tool and Floating Finishing 
Reamer. Cylinder boring and reaming tools which have 
proved very successful as applied to the cylinders of motors 
for one of the comparatively expensive automobiles are 
shown in Fig. 6. With this tool equipment it is claimed that 
cylinders can be reamed to within 0.00025 inch of being 
straight and round, and that the production, as compared 
with grinding, is in the ratio of 4 to 1. The first roughing 
tool used is shown at A. This tool is used on a horizontal 
Beaman & Smith four-spindle machine, and the holes are 
rough-bored to 3Vs inches in diameter. The four high-speed 
steel cutters are made of i/^-inch square stock and are held 
at an angle of 45 degrees. They are adjusted for varying 
the diameter by means of a central plug which is screwed 
in or out, thus changing the position of the conical seat 
against which the ends of the cutters bear. The clamping 
screws for holding the cutters in position are clearly shown 
in the illustration. This tool has a No. 5 Morse taper shank 
which enters a socket or holder having at the opposite end 
a flange which is bolted to the machine spindle. The holder 
is equipped with two cutters which serve to chamfer the 


42 CYLINDER BORING AND REAMING TOOLS 

crank end of the cylinder so that the piston packing rings 
will enter more readily. These cutters are attached to the 
holder in such a position that they come into action when 
the rough-boring tool has reached the end of its cut. 

Two semi-finishing cuts are next taken on a twelve-spindle 
Beaman & Smith machine of the same type as is illustrated 
in Fig. 6, Chapter I. This machine is equipped with tools 
of the type shown at B, Fig. 6. The bore is first enlarged 
from 3% inches to 3 3/16 inches with one group of spindles. 
Then the work-table is revolved to locate the casting under 
the second group of spindles, after which a third cut is 
taken, which increases the size to 3.240 inches. The tool 
used for the second and third cuts, like the first roughing 
tool, is adjustable for size. The adjustment is obtained by 
loosening the blades and turning the threaded collars at the 
rear. The collar adjacent to the blade has a 30-degree taper 
to correspond with the blade ends, and the slots in the body 
of the cutter have an inclination of 7 degrees, which pro¬ 
vides the .necessary radial adjustment. The blades are 
clamped by screws and hardened bushings flattened on one 
side to an angle of 3 degrees. 

The finishing reamer, which enlarges the bore to 3.250 
inches is shown at C, Fig. 6. This tool has eight high-speed 
steel blades which are held in place by pins having tapering 
flat sides. The cutter-head is mounted on an extension d 
of the reamer-bar, and it is driven by an intermediate plate 
e having tongues on each side located at right angles to each 
other like an Oldham coupling. The bore of the cutter-head 
is 1 inch and the diameter of the extension d is 0.995 inch, 
so that the cutter-head is free to float laterally 0.005 inch 
at this point. This universal floating movement is made 
possible by the Oldham coupling type of drive. The reamer- 
bar also has a floating connection to the shank. The exten¬ 
sion / on the shank is ground to a radius of 3 % inches, and 
the connecting pin passes through a hole which fits the pin 
only at the center as the illustration shows. This final 
reaming operation is done on a vertical single-spindle ma¬ 
chine, which is considered superior to a multiple-spindle 
type for this particular operation. The feed for reaming is 
0.016 inch per revolution, and the speed, 26 revolutions per 


CYLINDER BORING AND REAMING TOOLS 43 

minute, which is equivalent to a peripheral speed of 22 feet 
per minute. The blades of the finishing reamer are in¬ 
clined 10 degrees relative to the axis in such a way as to 
form a left-hand spiral. The reamer was made in this way 
to prevent chattering and to secure smoother reamed sur¬ 
faces. 

Adjustable Cutter-heads of Rigid and Floating Types. 

The roughing and finishing cutter-heads shown in Fig. 7 are 
designed to bore cylinders varying from 6 to 7 inches in 
diameter. Each tool has four cutters which are held in place 
by set-screws B and also by collars A. These collars are 
threaded to the body of the tool and provide means of ad- 



Fig. 7. Adjustable Cutter-heads of Rigid and Floating Types 


justment as well as a firm backing for the cutters. The tool 
shown in the upper part of the illustration is used for rough¬ 
ing and is a rigid design, whereas the lower tool is used for 
finishing and has a floating connection between the shank 
and the cutter body. The arrangement of this floating con¬ 
nection is clearly shown by the two sectional views. 

Single-point Tool in Connection with Reamers. A single¬ 
point boring tool is used for rough-straightening the cylin¬ 
der bores before reaming, at the plant of the Wilcox Motor 
& Mfg. Co., Saginaw, Mich. The order of operations is as 
follows: First operation, rough-boring with a four-blade 
tool; second operation, rough-straightening the bore with 


























44 


CYLINDER BORING AND REAMING TOOLS 



Fig. 8. (A) First Roughing Cutter. (B) Single-point Tool which 

follows Roughing Cutter. (C) Eight-blade Finishing Reamer 


a single-point tool; third operation, rough-reaming with a 
four-blade tool; fourth operation, finish-reaming with an 
eight-blade reamer. The first rough-boring tool or 
“reamer” is illustrated at A, Fig. 8. The diameter of this 

























































































































CYLINDER BORING AND REAMING TOOLS 


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plus or minus 0.002 inch. This tool is held at The three reamers referred to and the single- 
one side of the tool-head, as shown by the end point tool-head are all interchangeable with 
view, and the tool slot has an inclination of 15 the same size arbor. The construction of this 
degrees. The single-point tool is followed by a arbor is shown in Fig. 9. The rear end of 
second roughing reamer, which is practically each tool-head is threaded to fit a collar A which 































46 CYLINDER BORING AND REAMING TOOLS 

always remains on the arbor. The collar is knurled on the 
outside, and serves to draw the cutter-head back to the 
shoulder on the arbor. Two keys which project beyond 
the arbor shoulder engage slots cut across the rear side 
of the cutter-head and provide a positive drive. The arbor 
itself has a tongue B formed on each side to engage a cross¬ 
slot in the machine spindle. 

Machining End or Head of Cylinder. The compression 
ends or heads of cylinders for motors of the type used on 
automobiles, motor boats, etc., may or may not be machined, 
the practice varying in different plants and depending some¬ 
what upon the design of the cylinder. Some manufacturers 
finish the entire surface of the head end to obtain cylinders 
of uniform depth and a uniform compression in each cylin- 



Fig. 10. Under-cutting Tool used for counterboring Cylinders 


der when the motor is in operation. Other manufacturers 
allow these end surfaces to remain rough, and adopt other 
means of obtaining a uniform depth in each casting. In 
one large automobile plant, the rough unbored castings are 
set on the horizontal milling machine (which mills the 
crankcase ends and other flat exterior surfaces) with refer¬ 
ence to the head or compression ends of the cylinders. The 
castings are so located that the head ends are parallel with 
the table; hence each cylinder bore is practically the same 
depth as measured from the finished surface at the crank¬ 
case end. 

Some cylinders are slightly counter-bored at the inner 
end, and if this end is closed, it is possible to employ some 
form of expanding counterboring tool. An under-cutting 
tool of this type, which is used at the Peerless Motor Car 































CYLINDER BORING AND REAMING TOOLS 47 

Co/s plant for counterboring the cylinders, is shown in Fig. 
10. The tool A is attached to a holder B which is pivoted 
at C. An angular slot at the end of the holder engages a pin 
attached to a central bar D. At the upper end of this bar is 
a cross-pin which passes through an elongated slot in the 
body of the tool and enters holes in collar E. Any upward 
movement of this collar relative to the body of the tool 
forces the cutter outward, and vice versa. The collar is 
formed of two sections which are screwed together, and by 
adjusting the outer part, the point at which the tool begins 
to operate can be varied. The tool or cutter A is forced 
out to the working position when surface F of the collar 
comes into contact with the end of the cylinder. 



McCrosky Adjustable Cylinder Reamer. The reamer il¬ 
lustrated in Fig. 11, which is adapted for finishing cylinders, 
has six high-speed steel blades which are adjustable and are 
locked in position by drill-rod keys in conjunction with nickel 
steel clamping screws. Each blade has a drill-rod key em¬ 
bedded partly in it and partly in the reamer body, as shown 
by the end view, Fig. 12. The head of the clamping screw 
draws the key tightly against the blade with both a down¬ 
ward and lateral thrust. The blades are tapering along the 
lower edge, and the slots in the reamer body incline at a 
corresponding angle; consequently, when the blades are ad¬ 
justed in a lengthwise direction, by turning the threaded 
sleeves at the rear, the diameter is varied. These blades 
are adjusted forward to increase the reamer diameter, so 






























48 CYLINDER BORING AND REAMING TOOLS 

that they always project beyond the end and the reamer 
never loses its bottoming feature. This reamer is made by 
the McCrosky Reamer Co., Meadville, Pa. 

The six-spindle cylinder boring machine shown in Fig. 13 
is equipped with another design of adjustable reamer suit¬ 
able for cylinder work. This type has a threaded collar 
at the rear end of the blades and another collar recessed 
into the front end, and the adjustment is made by loosening 



Fig. 13. Cylinder Boring Machine equipped with 
Adjustable Reamers 

the rear collar, moving the blades along the inclined slots 
and then tightening the internal front collar. 

National-Cleveland Adjustable Cylinder Reamers. The 
cylinder reamers illustrated in Figs. 14 and 15 are designed 
for roughing and finishing cylinders without grinding. The 
manufacturer—the National Tool Co., Cleveland, Ohio—re¬ 
commends the use of two roughing reamers and one floating 
finishing reamer. The second roughing reamer should re- 








CYLINDER BORING AND REAMING TOOLS 49 

move about 0.080 inch stock, and the floating finishing 
reamer, 0.010 inch. The construction of the roughing 
reamer, Fig. 14, is practically the same as that of the fin¬ 
ishing reamer, except that it is not arranged for a floating 
action. The floating finishing reamer, as well as the one 
used for roughing, has eight high-speed steel cutting blades. 
Each blade is held by a locking screw, and in the center of 
the reamer there is a double cone adjusting plug which 



Fig. 14. Cylinder Reamer of Rigid Type 



Fig. 15. Cylinder Reamer of Floating Type 

serves to adjust the blades radially. This adjustment is ob¬ 
tained by turning the plug with a spanner wrench, thus 
forcing the radial pins and the blades outward when this is 
necessary to compensate for wear. The floating connection 
between the shank of the finishing reamer, Fig. 15, and the 
reamer body consists of a ball retainer having four slots 
spaced 90 degrees apart. Two of these slots engage driving 
pins in the cutter body, and the other two engage pins in 







50 CYLINDER BORING AND REAMING TOOLS 

the shank or driving end. This construction allows the 
cutter-head to float in any direction, so that it will follow 
the cylinder bore even though the latter is not in perfect 
alignment with the machine spindle. The ball retainer 
is enclosed by the shell which screws on the cutter body. 

Floating Parallel Reamer. The Martell floating parallel 
reamer made by the Taft-Peirce Mfg. Co., Woonsocket, R. I., 
is adapted for reaming cylinders and similar parts, and is 
designed to provide a free motion or floating movement at 
right angles to the axis of the spindle but to prevent any 
angular deviation from the axis. This reamer has a posi¬ 
tive drive which is so arranged that there is a free radial 
or lateral movement. The construction and the general 
arrangement of the parts will be apparent by referring to 
Figs. 16 and 17. The floating movement is derived from a 



Fig. 16. Reamer designed to float in a Lateral Direction only, 
or at Right Angles to Axis 

three-part coupling. One section is held by screws to the 
reamer shank and another part is secured in the same 
way to the reamer body, and there is an intermediate mem¬ 
ber, which serves to form two ball races at right angles 
to each other. These races are on opposite sides of the 
intermediate part and each contains two balls which reduce 
friction to a minimum. The driving flange of that part of 
the coupling attached to the shank is provided with two 
sector-shaped projections, and the driven end of the coupling 
is of similar form. The sector-shaped projections on the 
intermediate member mesh with the sectors of the coupling 
flanges, and the balls are inserted in intervening spaces. A 
cross-section on line A-A, Fig. 17, is shown in Fig. 18. This 
sectional view illustrates the sector-shaped projections re¬ 
ferred to, and shows the two driving balls on one side of the 
intermediate member. The two balls on the opposite side 













CYLINDER BORING AND REAMING TOOLS 


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17. This reamer has been called a “floating pa- again, and notwithstanding the fact that there 
rallel” type because it is designed to ream a hole was a heavy cut on one side and a light cut on 
that is parallel with the axis of the machine spin- the other side, it was found that the bore was true 
die even though the bore prior to reaming may and that it was in alignment with the machine 
incline somewhat. To test the effectiveness of the spindle. 






















































































52 CYLINDER BORING AND REAMING TOOLS 

Gisholt Shell Reamers. The straight-fluted shell reamer, 
Fig. 19, is adapted for reaming cast-iron cylinders. The 
right-hand spiral reamer, Fig. 20, is also satisfactory for 
cast iron but is especially suitable for steel. These reamers 
are made by the Gisholt Machine Co., Madison, Wis. When 
using a reamer having spiral or helical blades, the chips 
work out along the teeth more readily than when the teeth 
are parallel with the reamer axis. When reaming soft steel 
which tends to tear, or when it is necessary to remove an 
excessive amount of stock by reaming, the spiral-fluted type 
is considered greatly superior to the straight-fluted design. 
The blades of these reamers are held in grooves formed in 
the reamer body, thus securing the rigidity of a solid reamer 

and the advantage of an ad¬ 
justable type. The blades are 
adjusted by inserting beneath 
them thin pieces of paper or 
tin foil. A hard surfaced in¬ 
soluble paper, about 0.001 
inch thick, is recommended. 
Tin foil is used for finer 
adjustments. The adjusting 
strips may be inserted at the 
ends only, or the screws and 
blade may be removed and 
the strip placed under the 
full length of the blade. The spiral reamer has straight 
slots for the blades, the same as the straight-fluted type, but 
the spiral cutting edge is milled on the blade, each blade 
having one cutting edge. If the reamer does not become 
dull, this underlaying of the blades may be repeated more 
than once, but if dulling occurs, regrinding is necessary. 
The paper or tin-foil underlay is replaced for grinding with 
a metal strip thick enough to expand the reamer sufficiently 
to grind it to the desired size. It is recommended that the 
reamer be ground 0.0005 inch over size and slightly large in 
front, the taper not exceeding 0.00025 inch to each inch of 
length. The heel of each blade should be backed off with 
a cup-shaped wheel, leaving a land from 0.006 to 0.010 inch 
wide. 



Fig. 18. Cross-section on Line 
A-A of Reamer shown in Fig. 17 














CYLINDER BORING AND REAMING TOOLS 53 

Kelly Cylinder Reamers. The cylinder reamer shown in 
Fig. 21 has two high-speed steel blades or cutters A and B 
which are securely held in a steel plate C extending through 
a slot in the body of the tool. A tapered shoulder locking 
screw D passes through the plate which carries the cutters 
of the reaming tool. The tapered part of this screw engages 




Fig. 20. Right-hand Spiral Reamer 


a hole of corresponding taper in the reamer plate and 
provides for locking it rigidly in a central position for tak¬ 
ing roughing cuts or for regrinding the reamer blades. If 
this screw is slackened slightly, the reamer is allowed to 
float sidewise in the slot to compensate for any lack of align¬ 
ment in the machine. This floating movement should be in 
















54 CYLINDER BORING AND REAMING TOOLS 

the direction of the non-alignment of the machine, and then 
the reamer will reproduce its size. A floating movement 
equal to a few thousandths inch, or, in extreme cases, 1/64 
inch is sufficient to enable the reamer blades to locate them¬ 
selves centrally with the bore so that each blade or cutter 
will do an equal amount of work. 

Before using a floating reamer, it is recommended that 
the hole be bored true to within about 0.005 inch of the re¬ 
quired diameter; it should then be reamed before disturbing 
its central location as bored, so that the reaming operation 
simply removes the feed marks of the preceding tool. The 
high-speed steel blades of the reamer shown in Fig. 21 are 
inserted in a 10-degree dovetailed slot, and a 10-degree gib 
bushing holds them securely in place. At the rear of each 



blade, there is a hardened screw (see detail view) which 
gives a direct backing and prevents any change in the ad¬ 
justment of the blade. If the reamer is under size, it is 
adjusted by moving one blade outward an amount equal to 
one-half the error. The opposite blade is then adjusted out¬ 
ward until the dimension across the cutting edges conforms 
to the required diameter. On the other hand, if the reamer 
cuts a hole that is over size, the rear adjusting screw of one 
blade is turned backward far enough to allow this blade to 
be moved inward an amount equal to one-half of the error; 
the other blade is then moved inward until the distance 
across the cutting edges conforms to the required size. The 
clamp or gib bushing which bears against the side of each 
blade need not be loosened for making these adjustments, as 
the blades can be moved readily by rapping them with a 




















CYLINDER BORING AND REAMING TOOLS 55 

soft steel block. The reamer shown in Fig. 21 is one of the 
designs made by the Kelly Reamer Co., Cleveland, Ohio. 

Combination Boring and Reaming Tools. Tools designed 
for boring and reaming at the same time have been 
used quite extensively on some classes of cylinder work. 
One tool of this type, made by the Kelly Reamer Co., is 
shown in Fig. 22. This tool can be used when the cylinder 
is revolved and the tool is stationary, or when the work is 
stationary and the tool revolved, provided the cylinder has 
an open end so that a hardened pilot may be used to steady 
the tool. The boring tool is located ahead of a floating 
reamer, and as this tool is set to within about 0.003 inch 
of the required radius, it would not be satisfactory if the 
tool were revolving, provided there were any play in the 



Fig. 22. A Combination Boring and Reaming Tool 


spindle. This combination tool is considered an efficient 
type if held in a turret or if it can be provided with a pilot 
guide. 

A combined boring and reaming tool is used by the Root 
& Van Dervoort Engineering Co., East Moline, Ill., for 
machining the bores of Moline-Knight motors. These 
cylinders are first rough-bored in a four-spindle Moline 
cylinder boring machine. The tool used for the first rough¬ 
ing cut has a high-carbon steel blade with two pieces of 
half-inch square stellite brazed on, thus making a two- 
pointed cutting tool. The cylinders are rough-bored to with¬ 
in about 0.030 inch of the required size. They are then 
placed in another machine of the same kind, where the first 
reaming operation is performed. A floating Kelly reamer 





56 CYLINDER BORING AND REAMING TOOLS 

is used, the reamer being preceded by a fairly sharp pointed 
fly cutter. This fly cutter or single-point tool practically 
cuts a thread in the bore of the cylinder and tends to true 
up the hole which, owing to the heavy cut taken in rough¬ 
boring, is more or less inaccurate. The ridges left by the 
single-point tool are removed by the reamer, which imme¬ 
diately follows it, and in this operation the hole is enlarged 
to within from 0.004 to 0.005 inch of the finished size. 

The cylinder bores now have a good finish, but they are 
again reamed on a single-spindle Baker machine. An ad¬ 
justable multiple-bladed McCrosky reamer is used, and the 



Fig. 23. (Upper View) A Shell Drill having a Cylindrical Guiding 
Body. (Lower View) A Finishing Reamer 


object of this final reaming is simply to finish the hole ac¬ 
curately to size. As these motors are of the Knight type, 
two sleeves are required for each cylinder bore, and the 
holes in these sleeves are machined by practically the same 
methods as are employed for the cylinders. The method 
referred to has been adopted after several years of exten¬ 
sive experimenting. 

Morse Shell Drill and Finishing Reamer. The shell drill 
and expanding reamer shown in Fig. 23 have, according to 
the Morse Twist Drill & Machine Co., New Bedford, Mass., 
given very good results for roughing and finishing cylinder 
bores. The particular tools illustrated are intended for 



































CYLINDER BORING AND REAMING TOOLS 


57 


cylinders 41 / 8 inches in diameter. The shell drill has right- 
hand helical or spiral flutes, and it is 0.004 inch under the 
reamer size. Back of the shell drill, there is a cylindrical 
guiding part which is 0.002 inch smaller in diameter than 
the drill itself. 



Fig. 24. Shell Core Reamer adapted for Roughing Cuts 



Fig. 25. Expansion Shell Reamer for Finishing Cuts 


Peerless Shell Reamers. Two forms of “Peerless” 
reamers, made by the Cleveland Twist Drill Co., which are 
adapted for cylinder work, are shown in Figs, 24 and 25. 
The eight-blade reamer illustrated in Fig. 24 is the type 
recommended for roughing, and the twelve-blade design 
shown in Fig. 25, for finishing. This particular finishing 
reamer is of the expansion type. The end is split long- 





























58 CYLINDER BORING AND REAMING TOOLS 

itudinally in six places, and it is adjusted by screwing a 
central bushing in or out. This bushing has a tapering 
or conical surface, which provides the necessary adjust¬ 
ment, and it is turned by means of a keyed plug. Both the 
roughing and finishing reamers have high-speed steel blades. 
The blades are solidly joined to the reamer body, which 
is made of a special alloy steel, by a process termed “brazo- 
hardening.” 

Cutting Edges of Finishing Reamers. Sometimes diffi¬ 
culty is experienced with reamers used for finishing cylin¬ 
ders due to the fact that the blades are not properly sharp- 



Fig. 26. Cast-iron Lapping Ring for reducing Clearance on 
Reamer Cutting Edges 


ened. While the reamer must cut freely, it is essential to 
reduce the clearance to a minimum, not only to provide a 
stronger support for the cutting edge, but also to steady 
the reamer itself and prevent chattering. The National 
Tool Co., Cleveland, Ohio, recommends the use of the cast- 
iron lapping ring shown in Fig. 26, in case there is any 
chattering when using the reamers illustrated in Figs. 14 
and 15. This lapping ring is bored 0.003 inch larger than 
the reamer and it is about iy 2 inches wide. This lap is 
placed over the reamer blades and it is adjusted by means 
of a screw until there is a slight frictional resistance when 
it is turned by hand. After placing a little flour emery and 




CYLINDER BORING AND REAMING TOOLS 59 

oil in the ring, it is revolved a few times while being trav¬ 
ersed along the cutting edges. In this way the sharp 
razor edge which causes the reamer to cut with a slight 
chatter is removed. 

The reamer may require sharpening after a ten-hour 
run, although the length of time naturally varies consider¬ 
ably according to the nature of the material being reamed. 
When sharpening is necessary, the reamer blades are first 
adjusted by loosening the screws which hold them and 
turning the adjusting plug. The screws of two opposite 
blades are then tightened and these blades are measured for 
size. If the diameter is correct, the other blades are fastened 
in place. A three-cornered carborundum stone, 1/2 inch 
wide and of medium grade, is recommended for sharpening 
the blades. If the blades have been given too much clear¬ 
ance, the reamer will have a tendency to cut with a tremor 
or even with a chatter, and if this occurs, the ring lap 
previously referred to should be used. 

Pilots for Cylinder Reamers. The use of pilots on cylin¬ 
der boring and reaming tools may depend upon the design 
of the cylinder or upon the opinion of the tool designer, 
foreman, or superintendent as to the advantages of steady¬ 
ing tools by means of pilots. Many cylinders are so de¬ 
signed that the use of a pilot below the cutting tool would 
be impossible, simply because there is no opening in line 
with the center of the cylinder through which a pilot could 
pass. Even when there is an opportunity of using pilots, 
in most plants making automobile motors the boring and 
reaming tools of vertical-spindle machines are guided by 
bushings above the cutter-heads, these bushings being sup¬ 
ported by the bridge or top of the fixture. When pilots 
enter bushings below the cutting tools, there is often diffi¬ 
culty due to the entrance of chips and dust in the bushing 
hole. One method of overcoming this difficulty, at least 
partially, is to use either a leather or felt washer to exclude 
the chips and dust from the bearing surface. This washer 
is attached to the fixture at the top of the bushing and fits 
the pilot closely. Another method is to steady the pilot by 
means of rollers instead of using a plain bearing or bush- 


60 CYLINDER BORING AND REAMING TOOLS 

ing. The rollers themselves should be concealed and pro¬ 
tected as far as possible. The Continental Motors Co. has 
designed a fixture equipped with pilot rollers and intended 
for machines used for rough-boring cylinders. 

What is known as the “strip pilot” provides means of ad¬ 
justing the pilot itself to take up any play between the pilot 
and guide bushing. These strip pilots have been used by 
the Nordyke & Marmon Co. and they are also applied to 
some Kelly reamers. The pilot, instead of being in the 
form of a plain cylindrical extension, is provided with four 
hardened strips which are held by screws into grooves ex¬ 
tending lengthwise along the pilot. With this construction, 
any wear of the pilot or play between the pilot and bushing 
may be eliminated by placing liners back of the hardened 
strips and then regrinding them to the required size. Some 
Kelly reamers, designed especially for reaming cylinders 
having ports in the sides (such as the cylinders of two- 
cycle engines), have what are known as “hardened strip 
rear pilots.” The strips, in this case, are above the cutting 
tools and they fit closely into the finished bore of the cyl¬ 
inder, thus steadying the tool. This rear pilot also serves 
as a gage, in that it will bind in a cylinder bore which is 
not reamed up to the standard diameter. It is recommended 
that the cylinder be bored to within 0.015 to 0.020 inch of 
the final size before using the rear pilot type of reamer. 


CHAPTER III 


CYLINDER BORING AND REAMING FIXTURES 

The fixtures used for holding cylinder castings must be 
designed to some extent to suit the particular cylinder for 
which they are intended, but, in general, they are of the 
box type and partially enclose the cylinder, which is com¬ 
monly located by the engagement of dowel-pins with holes 
previously drilled and reamed. The same holes are also 
used to locate the cylinder for other operations. If the cyl¬ 
inder casting has a removable head, the boring is generally 
done from the top downward, the cylinder being held in the 
fixture in its natural position, assuming that a vertical type 
of machine is used. On the other hand, if the casting is 
solid and enclosed at the upper end, it must be held in an 
inverted position in the fixture, the boring being from the 
crankcase end of the cylinder toward the top. 

These cylinder boring fixtures are, in most cases, provided 
with a jig plate which extends from one side of the fixture 
to the other above the casting. This plate is provided with 
holes spaced to correspond with the center-to-center dis¬ 
tances between the cylinder bores, and it serves to guide 
and steady the boring and reaming tools. If the cylinder 
is of the closed-end type and is held in an inverted position, 
the finished face on the crankcase side is clamped against 
the jig plate, so that the cylinder bores will be square with 
the crankcase face after the machining operations. On the 
other hand, if the cylinder has a removable head and is held 
in its natural position, it is usually clamped against the 
base of the fixture. In any ease, a jig plate may be pro¬ 
vided for steadying the spindles of the boring machine and 
# the boring and reaming tools. In many instances, this 
jig plate has hardened and ground steel bushings to fit 
closely bronze bushings on the spindles which are steadied 


61 


62 


CYLINDER BORING AND REAMING FIXTURES 



Fig. 1. Cylinder Boring Fixture equipped with Movable 
Locating Pins and Wedge Clamps operated by a Handwheel 





Fig. 2. Fixture illustrated in Fig. 1 with a Cylinder 
Casting in Place 











CYLINDER BORING AND REAMING FIXTURES 63 

as the tools feed downward, so that they cannot be deflected 
laterally. Babbitt metal bushings are used extensively in 
preference to bronze bushings. These soft metal bushings 
should be so arranged that they can be adjusted to compen¬ 
sate for wear. A simple method is to provide a tapering 
hole for the bushing in the body of the fixture, and some 
form of ring or gland for forcing the bushing down into 
the tapering hole in order to reduce the diameter when ne¬ 
cessary on account of wear. When cylinder castings have 
removable heads or an opening at the end of the bore, the 
boring and reaming tools may be provided with pilots 
which extend downward and engage bushings below the 
cylinder casting. It is generally considered preferable, 
however, to equip the fixture with a jig plate that is located 
above the casting, on account of the trouble caused from 
chips and dirt entering bushings that are located at the base 
of the fixture. 

Boring Fixture with Movable Locating Pins. Fig. 1 shows 
the type of fixture used at the plant of the White Co., Cleve¬ 
land, Ohio. The fixture is shown applied to a Moline four- 
spindle cylinder boring machine. The cylinder casting is 
located by two dowel-pins which can be lifted up out of the 
way by means of handles A and B when inserting or remov¬ 
ing a casting. These dowel-pins are held in the upper posi¬ 
tion by turning the handles so that the pins engage a small 
horizontal slot at the top of the vertical slot. The dowel- 
pins engage two reamed crankcase bolt holes at each end of 
the cylinder, and the same holes are used for locating the 
cylinder casting for all boring and drilling operations. As 
soon as the casting has been inserted in the fixture and the 
dowel-pins have entered the locating holes, the finished 
surface of the casting is forced upward against the bridge 
or jig plate D extending across the top, by simply turning 
handwheel C at the base of the fixture, which serves to 
operate two wedges E beneath the cylinder casting. Fig. 2 
shows the fixture with the casting in place. This illustra¬ 
tion also shows clearly the four bushings which enter the jig 
plate and steady the machine spindles as the tools are fed 
downward through the cylinder bores. 



64 


Fig. 3. Fixture having Wedge and Cam-operated Clamps which act against Bottom and Flange of Cylinder Casting 

































































































































































































































































CYLINDER BORING AND REAMING FIXTURES 65 

Fixture with Wedge and Cam-operated Clamps. One de¬ 
sign of fixture used for holding Cadillac cylinders for the 
rough- and finish-boring operations is illustrated in Fig. 3. 



The finished face of the cylinder is held against plugs or 
buttons in the jig plate A of the fixture. These plugs pro¬ 
vide a better means of locating than a broad flat surface. The 

























































































66 


CYLINDER BORING AND REAMING FIXTURES 


casting is held in the correct position by dowel-pins B and 
C, which enter holes at the ends in the usual manner. This 
fixture has an ingenious arrangement for holding the cast¬ 
ing against bridge A before it is firmly clamped in position. 
As soon as the casting is inserted in the fixture, the weighted 
hand-lever D is thrown over from one side to the other, 
which forces two plungers up at the bottom of the fixture 
and holds the casting against the upper locating plugs. The 
shaft to which hand-lever D is attached is connected by 



Fig. 5. Fixture having Extensions to facilitate sliding Castings 
In and Out 


links E and F with wedges G and H, which force the plung¬ 
ers upward. This arrangement provides a quick method 
of forcing the casting against the upper part of the fixture. 
The casting is then fastened more securely by clamps J and 
K. These clamps are pushed upward by means of eccen¬ 
trics operated by hand-levers L and M. The fixture is also 
arranged for clamping the casting at the center, there being 
a hook-bolt N and a clamp 0 (see end view) which are 
drawn upward by lever P acting through eccentric Q and 







CYLINDER BORING AND REAMING FIXTURES 67 

the connecting link shown. Bushings are located in the 
bridge of the fixture for steadying the cutter-bars as they 
feed down through the bore. A sectional view of one of 
these bushings is shown at R. At each end of the bushing, 
there is a felt washer to prevent the dust and dirt from 
entering the bearing. These felt washers are held by metal 
washers and screws. When the fixture is in use, it is con¬ 
nected with the exhaust system at S. 

Four Clamping Wedges Operated by One Handwheel. 
Another design of cylinder boring fixture used at the Cadil¬ 
lac plant is illustrated in Fig. 4. This is similar in some 
respects to the one just described, but the lower clamping 
mechanism is entirely different. In this case, handwheel 
A operates screw B which is pivoted to yoke C. This yoke, 



Fig. 6. Cross-sectional View of Fixture Base showing Screw 
and.Bevel Gear Type of Clamping Mechanism 


in turn, is pivoted at the ends to smaller yokes which con¬ 
nect with wedges for operating the clamping plungers. 
These pivoted yoke connections between the screw B and 
the four wedges form an equalizing mechanism which uni¬ 
formly distributes the clamping pressure. The ends of the 
cylinder casting are further secured by clamps D and E 
which are forced upward by means of levers F and G 
through eccentrics or cams. 

Extensions on Fixture for Sliding Casting In and Out. 

The fixture illustrated in Fig. 5 is of the type which holds 
the casting against the upper part of the fixture. Two 
tracks or extensions are provided to facilitate sliding the 
casting in or out. The handwheels seen at the front of the 
illustration are for operating the clamping blocks which 

































68 CYLINDER BORING AND REAMING FIXTURES 

are located beneath the cylinder. The arrangement of this 
part of the fixture is shown by the cross-sectional view of 
the base, Fig. 6. The handwheel shaft carries a bevel pinion 
which meshes with a combination bevel gear and nut sur¬ 
rounding a screw attached to the clamping block; conse¬ 
quently, by turning the handwheel, the screw is raised or 
lowered. There are two of these clamping devices on each 
fixture. 

Fixtures for Open-end Cylinders. The fixture shown in 
Fig. 7 is designed for castings having separate or remov¬ 
able heads. The crankcase end of the casting is clamped 



Fig. 7. Fixture for Open-end Cylinders, having Sliding 
Work-holding Plate 


against a plate at the bottom of the fixture. This plate is 
mounted on parallel ways so that it can be pulled out in 
front of the fixture body for loading or unloading. The 
plate is located in the correct position for boring by a 
plunger which engages a hole in the fixture base. A similar 
fixture is shown in Fig. 8, except that it is designed for 
holding four-en-bloc cylinder castings. 

A simple type of cylinder boring fixture for holding cast¬ 
ings of the type having removable heads is illustrated in 
Fig. 9. The cylinder is located on the fixture by two dowel- 
pins in the base which enter holes in the flange. The same 








CYLINDER BORING AND REAMING FIXTURES 69 

locating holes are used for all other operations on the cast- 
ing, as in the previous case. The casting is held downward 


Fig. 8. Another Fixture of the Type having a Sliding 
Work-holding Plate 




Fig. 9. Simple Design of Fixture for Open-end Cylinders 

against the base of the fixture by two clamps. One is lo¬ 
cated at each end and bears against the top, as the illustra- 







70 


CYLINDER BORING AND REAMING FIXTURES 


tion shows. These clamps are held upward when the nuts 
are loosened, by springs around the bolts, so that they do 
not interfere with the insertion or removal of the work. 

Fixtures designed for holding castings against the base 
(which is the common arrangement for cylinders having re¬ 
movable heads) are often provided with mechanical means 
for raising the cylinder above the locating dowel-pins, when 
it is to be removed from the fixture. One such arrangement 
consists of a lever or crank connecting with a shaft carry¬ 
ing two cams which are in engagement with vertical plung¬ 
ers. When the casting has been bored and is to be removed, 



Fig. 10. Fixture equipped with Removable Work-holding Slides 


a turn of the operating crank or lever causes the plungers 
to force the casting above the dowel-pins so that it can be 
removed readily by the operator. 

Fixture with Removable Work-holding Slides. The fixture 
illustrated in Fig. 10 is designed for holding twin cylinder 
castings, and it is provided with work-holding slides B to 
which the castings are bolted in an inverted position, as 
indicated by the dot-and-dash lines. The fixture is intended 
for a four-spindle boring machine, and it is arranged to 
hold two cylinder castings at the same time. The body of 
the fixture is a cast frame of open construction, and the 
work-holding slides enter dovetail ways at the top. The 


































CYLINDER BORING AND REAMING FIXTURES 71 

castings are located on the slides by previously drilled and 
reamed holes in the flange, and they are held in position 
by clamps C. After a slide is pushed into the fixture, it is 
located by a plug D that engages a hole in the slide. In 
this way, both the slide and the cylinder casting are located 
in the correct position relative to the boring spindles of the 
machine. The casting is firmly supported on the lower side 
by tapered wedges which prevent any shifting of the work. 
A tie-bolt G extending across the top of the fixture serves 
to hold the slides rigidly. The nuts on these tie-bolts are 



released for removing the work-holding slides. This fixture 
was designed for a machine used exclusively for rough-bor¬ 
ing. Two extra work-holding slides were provided, so that 
the bored cylinders could be removed from one pair of slides 
and rough castings bolted to them while the machine was 
in operation, thus greatly reducing the idle or non-produc¬ 
tive period. 

Indexing Fixture for Reaming on Single-spindle Machines. 
When the cylinders of automobile and other motors having 
several cylinder bores cast en-bloc are reamed on a single- 



















































72 CYLINDER BORING AND REAMING FIXTURES 

spindle machine, some kind of indexing fixture is required. 
A simple design is illustrated in Fig. 11, which shows a 
front elevation. The cylinder casting, which is indicated by 
the dot-and-dash lines, is located by three pins A, and it 
is clamped against the upper part of the fixture by a central 
screw B, which operates a horizontal wedge engaging a ver¬ 
tical wedge. The body of the fixture C has a dovetailed 
bearing in the base D , and it is located in the four reaming 
positions by the holes E, F , G, and H in the base which are 
engaged successively by plunger J carried by the upper part 
of the fixture. This plunger is raised and lowered by lever 
K through the connection shown. 


CHAPTER IV 


CYLINDER GRINDING 

The grinding of engine cylinder bores in order to obtain 
a smooth accurate cylindrical surface is ordinarily con¬ 
fined to cylinders of internal combustion engines, because 
an accurate bore and a close-fitting piston are essential 
for motors of this class. The same degree of finish and ac¬ 
curacy is not necessary for the cylinders of steam engines, 
pumps, air compressors, and similar equipment, so the 
grinding process is not applied to work of this class except 
in a few special cases. The machines designed exclusively 
for cylinder grinding are used principally in the manufac¬ 
ture of engines for automobiles and airplanes (although 
they are often employed on other classes of work), and 
for this reason the practice to be described pertains almost 
exclusively to engines of the types mentioned. 

The two general methods of finishing cylinders that have 
been adopted by different automobile manufacturers are, 
first, boring and grinding, or boring, reaming, and grinding, 
and, second, boring and reaming, the reamer in the latter 
case being used for finishing, except when it is followed by 
a lapping operation. Whether or not cylinders can be fin¬ 
ished more economically by the grinding or the reaming 
methods may depend upon the design or type of cylinder, 
the class of service for which the motor is intended, as well 
as the care and intelligence exercised in the selection and 
use of the necessary tools and machines. 

Grinding vs. Reaming. In the automobile field, most 
manufacturers finish cylinder bores by grinding. In order 
to determine in a general way to what extent grinding has 
been adopted in preference to reaming, the practice of 
thirty representative manufacturers was ascertained, in¬ 
cluding the manufacturers of cars ranging in price from 


73 


74 


CYLINDER GRINDING 


the cheap to the expensive grades. Twenty of these con¬ 
cerns finish cylinders by grinding, and ten by reaming. 
Various reasons are given for the adoption of one method 
in preference to the other. Many contend that grinding 
is the only practicable method of securing the required de¬ 
gree of accuracy, but others believe that reaming is not 
only more rapid than grinding, but is just as accurate, 
assuming in each case that the tools are properly con¬ 
structed and applied. These differences of opinion are un¬ 
doubtedly due in part to the variable conditions which 
exist as regards either the tools used or the nature of the 
work. For instance, the results obtained by reaming may 
depend upon the design of the cylinder, the thickness of 
.its walls, the uniformity of different castings as to hard¬ 
ness, and the design and condition of the tool equipment. 
One reamer may cut smoothly and finish a cylinder bore 
within close limits of the required diameter, whereas an¬ 
other reamer, possibly of the same type, will chatter and 
leave a poorly finished hole. Frequently, such variations 
in the quality of the work are due entirely to the method 
of sharpening the reamers. The same line of reasoning 
applies to grinding, one manufacturer following approved 
practice in the selection of grinding wheels, or in properly 
machining the cylinders before grinding, and another not 
using the cylinder grinder to the best advantage. 

Objections to Reaming and Advantages of Grinding. The 

difficulties that seem to be the most prevalent in connection 
with the reaming of cylinders and the objections usually 
cited by manufacturers who have adopted the grinding 
method may be summarized as follows: (1) The spring¬ 
ing of the cylinder walls under the pressure of a cut, espe¬ 
cially if the walls are comparatively thin; (2) hard or soft 
spots in the cylinder which cause the reamer to be deflected; 
(3) open ports in the cylinder wall (in the case of two-cycle 
engine cylinders) which interfere with the reaming opera¬ 
tion; (4) the difficulty of keeping reamers sharp and cutting 
to the exact size required, especially when operating on the 
hard dense castings which are desirable for engines of the 
best quality; (5) the loss of compression and power in a 


CYLINDER GRINDING 


75 


reamed cylinder until it is worn in by running the engine. 
Just how important these objections are depends on condi¬ 
tions. For instance, the springing of the cylinder under the 
pressure of the cut may be very pronounced in the case of 
a light cylinder having a thin wall, but of no account as 
applied to a heavy cylinder casting. The second difficulty 
mentioned, arising from hard or soft spots in castings, may 
be due to poor foundry practice, especially if this lack of 
uniformity is the rule rather than the exception. While er¬ 
rors which may be traced directly to the tool itself show 
that some one reamer or type of reamer is not suitable, it 
does not follow that good work cannot be obtained by the 
reaming method. If the relative merits, however, of the 
reaming and grinding methods are to be based on actual 
practice, the conclusion is that grinding is considered pref¬ 
erable by most manufacturers, especially for motors of the 
best class (such as are used in automobiles and airplanes), 
which must withstand severe duty; reaming is employed 
more generally in manufacturing the cheaper grades of gas 
and gasoline engines of the kind used for various industrial 
purposes. The reaming method is more rapid than grind¬ 
ing, but the difference in this respect depends somewhat 
upon the time required to keep the reamers in good condi¬ 
tion and the degree of accuracy that is considered neces¬ 
sary. When cylinders are finished by grinding, there is no 
difficulty due to springing of the cylinder wall, because the 
pressure of the cut is very light if the proper grade of wheel 
is used, and the accuracy is not appreciably affected by 
hard or soft spots or by the side ports of two-cycle engine 
cylinders. 

Reasons for Variation in Practice. A few of the reasons 
given by representative automobile manufacturers for pre¬ 
ferring either the grinding or the reaming method will be 
given in order to illustrate to what extent opinions differ: 

“All cylinder bores are finished by boring and grinding. 
We tried very hard to get the desired results by reaming, 
but have discarded this method and believe that boring and 
grinding is the only practicable way of finishing cylinder 
bores within the desired limits of accuracy in quantity pro- 


CYLINDER GRINDING 


76 

duction. A cylinder may be reamed satisfactorily if the 
reamer is sharp and properly applied, but when the cutting 
edges are a trifle dull and the reamer is forced a little, good 
results are not obtained, as the cylinders will be over size, 
tapered, and out of round. The finish obtained by reaming 
is not smooth enough, and soon after the motor is in opera¬ 
tion the surface will wear down, thus increasing the cylin¬ 
der diameter and the clearance between the cylinder wall 
and piston sufficiently to cause trouble. The cylinders fin¬ 
ished by grinding are held within limits of 0.0005 inch 
plus or minus, and they are straight and round within an 
error of 0.0005 inch. We have been unable to obtain such 
accuracy by reaming, the reamed cylinders in many cases 
being as much as 0.004 or 0.005 inch out of round and 
tapered. If the reamed cylinder is checked by accurate 
measurement at the top and bottom flanges, it is fairly 
round, but in between the flanges where the cylinder wall 
is unsupported and in many cases a little thinner due to 
shifted cores, the cylinder wall will spring away from the 
reamer which does not produce a perfectly round or straight 
bore.” 

“At the present time, all standard cylinders are finished 
by reaming. The bores can be reamed within 0.00025 inch 
of being straight and round, which is better than we could 
do by grinding. The reaming method also increases produc¬ 
tion in the ratio of 4 to 1. A single-spindle machine is used 
for the final reaming operation. Attempts have been made 
to finish-ream on a multiple-spindle machine, but as yet the 
results have been unsatisfactory. An eight-blade left-hand 
spiral floating reamer is used for finishing.” 

“While a properly reamed cylinder will give fully as good 
service as a ground one, we have adopted the grinding 
method. The principal trouble with reaming is the difficulty 
in obtaining reamers that will hold their size and produce 
a uniform smooth finish. It is on account of the upkeep of 
reamers that the grinding method of finishing cylinder bores 
is preferred.” 

“We have had considerable experience with both reamed 
and ground cylinders, and have found that the ground cyl- 


CYLINDER GRINDING 


77 


inder proves to be the best not only from a quality standard, 
but also from an economical viewpoint, taking into con¬ 
sideration the extra amount of work that must be expended 
in the test room in order to produce a first-class job.” 

“The cylinders of engines for passenger cars are finished 
by boring and grinding, and truck engine cylinders by bor¬ 
ing and reaming.” 

“Cylinder bores are finished by boring and reaming. This 
method has given good results and as many as three hundred 
cylinders have been finished before changing reamers. The 
reamer is a six-blade left-hand spiral type secured to a 
floating bar. It produces a smooth straight hole and cuts 
without vibration or chatter.” 

“Our entire output consists of tractor motors, and we 
consider that the reamed cylinder is satisfactory for this 
class of service. A four-blade roughing reamer is used, 
followed by an eight-blade finishing reamer.” 

Eccentric-head Cylinder Grinder. The common practice 
of forming two or more cylinder bores in one solid casting 
or en-bloc makes it desirable to devise a method of grinding 
cylinders without revolving them on account of the difficulty 
of rotating a large casting and of counterbalancing it, es¬ 
pecially when boring the end cylinders. The adjustment of 
the cylinder casting for obtaining the correct center-to- 
center distance between the bores was another point to be 
considered. The planetary or eccentric-head type of 
grinder, which is now in common use, is so arranged that 
the cylinder casting remains stationary while being ground, 
and it can be adjusted accurately for finishing the different 
bores in accordance with whatever center-to-center distance 
is prescribed. The principle of this machine is very simple. 
The grinding wheel, as it revolves rapidly about its own 
axis, is given a relatively slow circular or planetary motion, 
so that it is carried around the wall of the cylinder. At 
the same time, the cylinder, which is mounted on a carriage 
or slide of the machine, is given a lengthwise feeding move¬ 
ment which, for each complete circular movement of the 
wheel around the cylinder wall, is somewhat less than the 
width of the grinding wheel. The spindle-head of the grind- 



Fig. 1. Cylinder Grinder grinding a Two-en-bloc Casting 



78 


Fig. 2. Battery of Cylinder Grinders 















CYLINDER GRINDING 


79 

ing machine is so arranged that the eccentricity of the 
wheel-spindle or the diameter of the circular path it follows 
can be varied for grinding to the diameter required. 

A cylinder grinding machine made by the Heald Machine 
Co., Worcester, Mass., is shown in Fig. 1, with a two-en- 
bloc cylinder mounted on the work-holding fixture. Inde¬ 
pendent drives are provided for the wheel-spindle and for 
the wheel-head, or the outer eccentric sleeve which contains 
the wheel-spindle and gives the latter its planetary motion. 
The arrangement of the driving belts is illustrated more 
clearly in Fig. 2, which shows a battery of these machines 
at the factory of the Packard Motor Car Co. One belt from 
the overhead countershaft drives the wheel-spindle through 
an intermediate connecting belt. A second belt from the 
overhead countershaft connects with a pulley near the base 
of the machine, which, through intermediate belts and gear¬ 
ing, drives the grinding-head or wheel-head and transmits 
a feeding movement to the work-table. A gear-box at the 
end of the machine provides four different speeds of rota¬ 
tion for the wheel-head, so that the planetary motion of the 
wheel can be varied for taking roughing and finishing cuts. 
A second gear-box, at the front of the machine column, 
gives three rates of feed for the work-table for each speed 
of the wheel-head. The feeding movements are independ¬ 
ent of the rotary speeds of the wheel-head. The traversing 
movement, or stroke of the work-table, is adjusted by dogs 
at A and B, Fig. 1, which control the point of reversal. The 
work-table is arranged for a continuous reciprocating mo¬ 
tion, but a stop is provided for disengaging the table feed 
at the point of reversal. On the main work-table there is 
a cross-slide which carries the work-holding fixture. This 
cross-slide has adjustable stops to locate the cylinder ap¬ 
proximately for grinding the different bores. The exact 
center distance is indicated by a micrometer dial on the 
cross-feed screw. 

The depth of cut or diameter of cylinder bore can be 
regulated by the mechanism which varies the eccentricity 
of the wheel-spindle. If a rather large adjustment is neces¬ 
sary, a crank is applied to worm-shaft F , whereas for small 
adjustments, knob C is used. If the wheel-head is revolv- 


80 


CYLINDER GRINDING 



ing slowly, this knob would ordinarily be employed for 
varying the depth of the cut, but if the wheel-head is rotat¬ 
ing at the higher speeds, as for finishing, lever D is shifted, 
thus causing a star-wheel to turn one notch for each rota¬ 
tion of the wheel-head, which adjusts the wheel to an 
amount equal to about 0.00025 inch in radius. After one 
cylinder has been ground to the right diameter, dial E is 
set to the zero position and worm-shaft F is turned back¬ 
ward about one revolution, or far enough so that the wheel 
will clear the next hole to be ground. When grinding the 


Fig. 3. Cylinder Grinder with Work in Position for grinding 

next hole, the wheel may be fed in until dial E is again 
returned to the zero position. In this way unnecessary gag¬ 
ing or calipering is eliminated, and the graduations on the 
dial will greatly assist the operator in removing a given 
amount from the cylinder bore. As a true wheel is essen¬ 
tial in cylinder grinding, diamond tools are used for truing, 
and these are generally attached to the face of the jig, as 
indicated at G in the illustration. 

Another cylinder grinding machine of the eccentric head 
or planetary type is illustrated in Fig. 3. One belt from the 












CYLINDER GRINDING 


81 


overhead countershaft drives the wheel-spindle through an 
intermediate connecting belt, and a second belt rotates the 
wheel-head. The pulley for driving the wheel-head has two 
steps or diameters which provide two speed changes. Mo¬ 
tion is transmitted to the outer eccentric sleeve through 
gears.. The fixture on which the cylinder :s supported is 
dovetailed to the carriage of the machine and can be ad¬ 
justed laterally by the handle shown. The faceplate, to 
which the cylinder casting is clamped, is provided with 



Fig. 4. Cylinder Grinder operating on a Six-en-bloc Casting 


vertical adjustment. The eccentricity of the wheel-spindle 
is varied by a small knurled handle, which is graduated to 
represent thousandths of an inch. This machine is manu¬ 
factured by B. L. Schmidt Co., Davenport, Iowa. 

Cylinder Grinder with Grinding Head Cross Adjustment. 

The cylinder grinding machine to be described is so de¬ 
signed that the work-holding table is traversed parallel to 
the axis of the grinding-wheel spindle, but the cross adjust¬ 
ment for locating the wheel in alignment with different 
cylinder bores is obtained by changing the position of the 




CYLINDER GRINDING 


82 

grinding head. This machine is illustrated in Fig. 4, and, as 
will be seen, the grinding head or wheel-head is mounted on 
ways extending across the machine. A uniform tension is 
maintained on the driving belt, regardless of the position of 
the wheel-head, by an automatic belt-tightening device. 
After the cylinder has been mounted on the work-table, it 
is simply traversed with the work-table to obtain the neces¬ 
sary feeding movement, but the wheel-head is shifted in 
order to locate successive holes in position for grinding. 
The traverse of the table is controlled automatically by ad¬ 
justable dogs which regulate the points of reversal. The 
wheel-head is of the double eccentric construction, which 
provides the necessary adjustment, and a micrometer dial is 
furnished to facilitate grinding accurately to the required 
size. This machine is the product of the Madison Machine 
Tool Co., 609 E. Washington Ave., Madison, Wis. 

Rotation of Wheel-head and Feeding Movement of Cy¬ 
linder. When a cylinder is being ground, the distance that 
it is fed in a lengthwise direction for each complete travers¬ 
ing movement or revolution of the wheel-head may vary 
from a fine feed up to about three-quarters of the wheel 
width. This relation between the rotation of the wheel- 
head or the planetary motion of the wheel around the 
cylinder wall, and the feeding movement of the cylinder 
itself, depends upon the hardness of the casting, the kind of 
wheel used, and the amount of metal to be removed by 
grinding. Even if all castings were exactly alike as to hard¬ 
ness and all grinding wheels absolutely uniform, a standard 
could not readily be established because of variations in 
the machines themselves, either as to design or condition. 
A new machine, to obtain the best results, might require a 
different method of operation than a much older machine 
of the same make, particularly if the latter were not in a 
good state of repair. 

When taking roughing cuts, it is common practice to re¬ 
volve the wheel-head at a slower rate than for finishing cuts 
(although the speed is sometimes reduced for finishing), and 
the feeding movement of the cylinder is equal to about one- 
half or three-quarters of the wheel width. A feed of three- 


CYLINDER GRINDING 


83 

quarters of the wheel width and light cuts are considered 
advisable if there is little stock to remove. If the grinding 
allowance is quite large, or the metal is rather hard to 
grind, deeper cuts and a finer feed are usually preferable. 
The leading corner of.the wheel then does much of the 
work, and it is good practice to reverse the wheel on the 
spindle occasionally to distribute the wear on both sides. 

Both coarse and fine feeds are used for finishing, the 
practice varying. The coarse feed, combined with light 
cuts, increases production and leaves a good surface if a 
true wheel is used, but many prefer finer feeds in order to 
eliminate slight feed marks and secure a smoother finish. 
Soon after an engine is in service, there will be no percepti¬ 
ble difference between the cylinders finished with the fine 
and with the coarse feeds, other things being equal. The 
wheels commonly used are % inch wide. This width per¬ 
mits using a little softer grade than the l/^-inch wheel, 
which formerly was quite generally used, and the wider 
wheel tends to decrease the time for grinding. The wheel 
should be trued before taking the light finishing cuts. 

Circulating Water through Cylinder Jacket. Water is 
often circulated through the jackets of cylinders while 
grinding the bore, in order to maintain a uniform temper¬ 
ature in the cylinder casting and prevent distortion. When 
a cylinder is ground without circulating water through 
the jacket, the heat generated by the grinding wheel causes 
the cylinder to expand. If the finishing cut is taken before 
the cylinder cools, the size of the bore will be reduced some¬ 
what when the cylinder is cold and it may contract unevenly, 
owing to unequal distribution of metal in the casting; con¬ 
sequently it is difficult for the grinding machine operator to 
determine the allowance for this expansion, and as the cylin¬ 
der is finished while heated, it may not be truly cylindrical 
when cold. To overcome these difficulties and maintain a 
uniform temperature in the casting, it is generally consid¬ 
ered preferable to circulate water through the jacket and 
over the outside of the cylinder near the crank end or below 
that part of the cylinder which is not surrounded by the 
water jacket. 


84 


CYLINDER GRINDING 


The most common practice is to use cold water, but some 
manufacturers prefer hot water. The object of circulating 
hot water through the jacket instead of cold is to grind the 
cylinder under conditions similar to those existing when 
the engine of which the cylinder forms a part is in actual 
use. The contention is that if the cylinder is ground true 
while heated by hot circulating water, it will assume this 
form, approximately at least, when heated while in service 
The advantage of using hot water to obtain a true bore 
under operating conditions may depend considerably upon 
the design of the cylinder to be ground. Some cylinder 
castings expand and contract more uniformly than others. 
If the distribution of metal is such that the expansion 
causes considerable change in the shape of the bore, the 
greater degree of accuracy obtained by the hot water method 
may more than offset its disadvantages. As a general rule, 
it is much more convenient to obtain a supply of cold water 
than hot water. Another point to consider is the matter of 
inspection, as it is more difficult to finish cylinders within 
the prescribed limits of accuracy when the work is ground 
while hot, and inspected while cold, than when both the 
grinding machine operator and the inspector measure a 
cold cylinder. 

Circulating Steam through Jacket while Grinding. Steam 
has been used by a few engine manufacturers for heating 
cylinders while grinding the bore, in order to grind them 
under temperature conditions at least somewhat similar to 
the actual working conditions. Fig. 5 illustrates the grind¬ 
ing of a two-en-bloc cylinder casting while heated to about 
212 degrees F. The pipe supplying the steam is attached 
to the head end and connects with the steam heating system. 
The steam was allowed to pass through the water jacket 
and out of the small cock seen at the top of the casting near 
the crankcase end. A flexible hose connection is provided 
for the steam pipe to permit moving the cross-slide of the 
machine far enough to align the wheel with the two cylinder 
bores. The large pipe seen entering the cylinder is for 
exhausting the dust. When cylinders are ground while 
heated, they become distorted more or less when the casting 


CYLINDER GRINDING 


85 


is cool. In this particular case, the measurements made 
after the cylinder had cooled showed a distortion of about 
0.003 inch, the cylinder tapering and being small at the 
explosion end. 

Wet and Dry Methods of Grinding. The general practice 
is to grind cast-iron cylinders dry or without applying 
soda water or any other cooling medium to the wheel. The 
application of water should be confined to the water jacket 
and to the outside of the cylinder at the crank or unjacketed 
end. According to the experience of the Heald Machine Co. 
on tests made with wet grinding, this method reduces the 



Fig. 5. Cylinder connected with Steam Pipe for circulating 
Steam through Jacket while grinding Bore 


efficiency of the grinding operation. The wheel cuts to 
better advantage when operating dry, and a better finish 
or surface is left in the cylinder bore. A wet wheel also 
tends to become loaded with dirt, which is not the case 
when grinding with a dry wheel of the right grade. 

Allowances for Cylinder Grinding. The allowance for cyl¬ 
inder grinding is about 0.008 or 0.010 inch under average 
conditions. The time required for finishing a cylinder bore 
by grinding may be affected considerably by the allowance. 
It is advisable to remove as much metal as practicable by 
the boring and reaming tool. The grinding allowance in 
some cases is as high as 0.040 or 0.050 inch, but it is not 



86 CYLINDER GRINDING 

economical to remove so much metal by grinding. Exces¬ 
sive allowances are often due to neglect in maintaining 
the boring or reaming tools to the proper size. In some 
instances, cylinders are bored under size, so that they will 
be sure to “clean up” or be ground true. Under favorable 
conditions an allowance of 0.004 or 0.005 inch might re¬ 
duce the grinding time, although as a rule this is working 
too close to the finished size and approximately 0.010 inch 
is preferable. Some manufacturers, however, have 
adopted these small allowances in order to reduce the 
grinding time, but they do the boring and reaming care- 



Fig. 6. Grinder operating on Forged Steel Cylinder of an 
Airplane Motor 

fully. The cylinder bore prior to grinding need not have 
a smooth finish, but the bore should be true and square 
with the finished face of the cylinder flange, because it is 
more economical to prevent excessive errors in machining 
than to correct them by grinding. 

Grinding Airplane Engine Cylinders. The grinding of cyl¬ 
inders for airplane engines differs somewhat from ordinary 
cylinder grinding practice as applied to the cast-iron cylin¬ 
ders of engines for automobiles, trucks, motor boats, etc., 
partly because of the delicate construction of the cylinder. 
The machine illustrated in Figs. 6 and 7 is arranged for 
grinding the cylinders of Liberty motors. This is a deep- 





CYLINDER GRINDING 


87 


hole grinding machine made by the Bryant Chucking 
Grinder Co., Springfield, Vt. These airplane engine cylin¬ 
ders are steel forgings, and as the walls are very thin, it is 
of especial importance to equip the grinding machine with 
a fixture that will hold the cylinder for the grinding oper¬ 
ation without any springing or distortion of the work. 

The interesting design of the fixture developed for this 
class of work is shown by the sectional view, Fig. 8. The 



Fig. 7. Another View of the Grinder shown in Fig. 6, arranged for 
Airplane Cylinder Work 


heavy black line in this illustration represents a section 
of the cylinder. This cylinder has a 5-inch bore and a 
grinding length of 11 inches. The fixture is in the form of 
a pot chuck, and almost entirely encloses the cylinder which 
is held in an auxiliary loading sleeve. The cylinder is first 
clamped in the loading sleeve, as shown by the detail view, 
Fig. 9. This sleeve A has five clamps of the type shown at 
B which hold the external flange of the cylinder firmly 
against a finished face of the loading sleeve. The sleeve 









































































































































































































CYLINDER GRINDING 


89 


and the cylinder as a unit are then placed in the main 
chuck, as shown in Fig. 8. The loading sleeve has conical 
surfaces at C and D, which engage corresponding surfaces 
in the chuck, thus accurately centering it. The sleeve is 
held in position by two clamps E. In order to steady the 
cylinder further without subjecting it to a clamping pres¬ 
sure that would cause a distortion of the thin wall, a spring 
plunger is located at F, which has a three-point contact and 
is held against the end of the cylinder by spring G. 

Two loading sleeves are used with this method of chuck¬ 
ing, which permits the operator to insert a cylinder in one 



Fig. 9. Loading Sleeve in which Cylinder is placed before 
inserting into Main Fixture 


sleeve while the machine is grinding a cylinder held in 
the other sleeve. These loading sleeves are also interchange¬ 
able with chucks on different machines, so that, if neces¬ 
sary, a sleeve and a cylinder can be kept together as a unit, 
and passed from one machine to another as might be re¬ 
quired for roughing and finishing operations. The machine 
used for this work has an unusually long work-holding 
spindle to compensate for the long overhanging work chucks 
used for deep-hole grinding. Notwithstanding the unusual 
length between the work-spindle bearings, it is sometimes 
desirable, in the case of unusually long work, to use a 
steadyrest or outboard bearing for supporting the outer 
end of the work-holding chuck. 































90 


CYLINDER GRINDING 


When the machine is in operation, the cylinder, of course, 
revolves while the wheel is traversed through it. The 
grinding is done wet, water or a suitable cooling compound 
flowing directly into the cylinder bore. The water passes 
through part H extending through the machine spindle, 
and then through the flexible tubes J and K which pass 
through holes in the head end of the cylinder. The object 
of applying water directly to the bore when grinding these 
steel cylinders is to obtain as smooth a finish as possible 
and cool the cylinder wall uniformly so as to permit grind¬ 
ing faster without danger of distorting the wall by gener¬ 
ating excessive heat. 

After the boring operation, the cylinders have about 0.038 
inch stock to be removed by grinding. About 0.030 inch 
is removed by a rough-grinding operation and the remain¬ 
der by finish-grinding. Under average conditions, five 
cylinders are rough-ground per hour, and forty-seven 
cylinders have been rough-ground in nine hours on one 
machine. A 38-36 grade J alundum wheel was used, having 
a 34-inch face and a diameter of 4i/ 2 inches. Experience 
has demonstrated that for the roughing operation, the 
machine will remove, on an average, 0.002 inch stock per 
minute (this time includes chucking the work), assuming 
that the cylinders have over 0.025 inch stock to remove. 
For operations of this kind, the ball bearing wheel-head 
shown at A , Fig. 10, is used. While this wheel-head is 
considered preferable for the roughing operation, it will 
not produce the fine surface required for the finished cylin¬ 
der, and the bronze bearing wheel-head shown at B is used 
instead. 

The average time for the finishing operation is approxi¬ 
mately fifteen minutes per cylinder, and the average time 
for both the roughing and finishing operations is about 
thirty minutes per cylinder. At the Ford Motor Co. thirty 
airplane engine cylinders have been finish-ground in eight 
hours on one machine, and all of them passed the govern¬ 
ment inspection. The wheel used for the finishing operation 
was a 38-46 grade H or I alundum wheel, having a 1-inch 
face and a diameter of 41/2 inches. 


CYLINDER GRINDING 


91 





Fig. 10. Grinding Wheel-heads used for Roughing and Finishing Operations 



































































































































































































92 


CYLINDER GRINDING 


The table traverse for the roughing operation is about 
3/16 inch per revolution of the work. The same rate of 
traverse is employed for finish-grinding until the cylinder 
is within about 0.003 inch of the finished size; then the 
slower traverse of about 1/16 inch per revolution of the 
work is used to obtain a finer finish. 

Another example of airplane engine cylinder grinding is 
illustrated in Fig. 11. This view shows a Heald machine 



Fig. 11. Another Example of Airplane Cylinder Grinding 

grinding a cylinder at the plant of the Hall-Scott Motor Car 
Co., Berkeley, Cal. In this case the cylinder is cooled by 
circulating water through the jacket. There are two water 
pipes, one connecting with the head end and the other with 
the lower end, thus providing a continuous circulation. The 
large pipe having a nozzle which extends to an opening on 
the lower side of the cylinder head, is for exhausting the 
dust and cooling the cylinder. 







CYLINDER GRINDING 


93 


Fig. 12 illustrates how airplane cylinders are tested after 
grinding at the shop of Lewis & White, Syracuse, N. Y. An 
Ames dial gage is mounted on a base which is in contact 
with the cylinder bore along each side. As this base is 
pushed through the cylinder, with the indicating point of 
the gage bearing against the side of the cylinder, any diam¬ 
eter variations are readily detected. This simple form of 
gage not only shows any taper in the bore, but also indicates 
lack of roundness, the cylinder being turned so that the 
diameter can be tested across different parts of the bore. 



Fig. 12. Testing Accuracy of Ground Airplane Cylinders 

This general type of gage has also been used extensively for 
testing cylinders of automobile and airplane motors. 

Cylinder Grinding in Automobile Plants. The cylinder 
bores of engines for the more expensive cars are almost 
invariably finished by grinding. While there is no definite 
dividing line, as a general rule if the selling price of a car 
is more than a thousand dollars, it usually has ground 
cylinders, whereas if the price is less than the sum men¬ 
tioned, the reaming method (possibly followed by a lapping 
operation) is more generally employed than grinding. This 







94 CYLINDER GRINDING 

is due to the fact that a cylinder can be reamed much more 
quickly than it can be ground, as far as the actual machin¬ 
ing time is concerned. A few examples of cylinder grind¬ 
ing, taken from different automobile plants, will be referred 
to in order to illustrate some of the variations in practice. 

One of the cylinder grinding machines used by the White 
Co., Cleveland, Ohio, is illustrated in Fig. 13. This view 
shows a four-en-bloc cylinder after the grinding operation. 
The cylinders are first bored and then reamed on a vertical 
multiple-spindle machine to within 0.008 or 0.010 inch of the 



Fig. 13. Grinding Cylinder after Reaming Operation 


finished size. Before the grinding operation, the cylinder 
castings are heated to a temperature of 500 degrees F. for 
a period of four hours in order to relieve the internal 
stresses and prevent them from being distorted by the heat 
generated when the motor is in operation. The fixture for 
holding the cylinder while grinding is provided with two 
dowel-pins at A and B which govern the location of the cyl¬ 
inder. These dowel-pins are in the same relative positions 
and enter the same holes as the dowel-pins of the boring and 
reaming fixtures previously used. During the grinding 
operation no water is circulated through the jacket or over 







CYLINDER GRINDING 


95 


the outside of the cylinder, as this is not considered neces¬ 
sary. The practice is to rough-grind each bore and then 
take a light finishing cut. If the bore to the extreme right 
is the first one to be rough-ground, the finishing cut in 
this bore is not taken until the other three bores have been 
rough-ground; consequently, each cylinder bore is allowed 
to cool after the rough-grinding operation and before taking 
the finishing cut. The wheel-head of this machine revolves 
about 80 revolutions per minute, which represents the rate 
at which the wheel traverses around the cylinder wall, and 



Fig. 14. Grinding Four-en-bloc Cylinders (Example of Grinding 
without the Use of Circulating Water) 

should not be confused with the speed of the spindle, which, 
of course, revolves very rapidly. The cylinder grinding 
machine shown in this illustration was formerly made by 
the Brown & Sharpe Mfg. Co., but is now manufactured by 
Baxter D. Whitney & Son, Winchendon, Mass. 

A cylinder grinding operation at the plant of the Cadillac 
Motor Car Co. is illustrated in Fig. 14. This particular il¬ 
lustration shows the grinding of four-en-bloc cylinders hav¬ 
ing the heads cast solid. The present design of cylinder has 
a removable head, although the grinding operation is the 
same in each case. The cylinders are reamed to within ap- 





96 


CYLINDER GRINDING 


proximately 0.010 inch of size before grinding. This is an¬ 
other example of cylinder grinding without the use of cir¬ 
culating water in the jacket. The cylinders are ground to 
within 0.002 or 0.003 inch of the finished size, and are then 
allowed to cool before taking the light finishing cuts. The 
lower part of the cylinder has a length of about 3% inches 
which is not surrounded by a jacket; therefore, if water 
were used in the jacket, it would be necessary to cool the 
unjacketed end by pouring water over the outside, and in 
order to avoid this, the method previously referred to is 



Fig. 15. Cylinder Grinder equipped with Dust Exhauster and Pipes 
for circulating Water through Jacket and over Unjacketed End 


followed; that is, the heat generated by the roughing cut is 
allowed to dissipate before taking the finishing cut. The 
cylinder bores are ground to 3.125 inches, usually within a 
limit of about 0.001 inch, although a tolerance of 0.002 inch 
is allowed. The wheel-head makes 80 revolutions per min¬ 
ute, and the feeding movement of the wheel through the 
cylinder bore is at the rate of about 6i/ 2 inches per minute 
for both the roughing and finishing cuts. This feeding 
movement is equivalent to approximately 3/32 inch per re¬ 
volution of the wheel-head. About 0.002 or 0.003 inch of 





CYLINDER GRINDING 


97 

stock is removed by each roughing cut; usually two in-and- 
out traversing movements, or four cuts through the cylinder 
bore, are required for roughing, and about the same num¬ 
ber of very light cuts for finishing. The pipe for exhausting 
the dust caused by grinding and for cooling the cylinder 
may be seen in the illustration at the head end of the cylin¬ 
der. It will be noted that this pipe is inserted opposite 
whichever bore is being ground. 

The practice of the Hudson Motor Car Co. in machining 
cylinder bores is to make the' bores as accurate as practic- 



Fig. 16. Grinding the Sleeves of Engine Motors 


able before attempting to grind them, thus reducing grind¬ 
ing time to a minimum. Three cuts are taken through the 
bore prior to grinding. First, there is a heavy roughing 
cut, and then a lighter roughing cut, followed by a reaming 
operation which enlarges the bore to about 3.496 inches 
before grinding to 3.500 inches. The allowance for grind¬ 
ing, therefore, is only 0.004 or 0.005 inch, subject, of course, 
to slight variations. It has been found more economical to 
machine the cylinders close to the finished size than to be 
less careful with the boring and reaming operation and 






CYLINDER GRINDING 


98 

remove a larger amount of stock by grinding. Usually, 
about four traversing movements of the wheel through the 
bore are required for the grinding operation. Fig. 15 shows 
the machine grinding the second bore from the left, as in¬ 
dicated by the position of the dust exhaust pipe which leads 
to the main exhaust line above. The cylinder is water- 
cooled during the grinding operation. There are two pipes, 
as shown, for supplying the cooling water. One pipe leads 
to the cylinder jacket, and the other extends beneath the 
casting and is perforated to spray water over the unjack- 



Fig. 17. Grinding a Six-en-bloc Casting 


eted end of the cylinder. It is claimed that these cylinders 
are ground within a limit of 0.001 inch on the diameter, 
and accurate as to taper or roundness within 0.0005 inch. 

The Heald cylinder grinding machine illustrated in Fig. 
16 is arranged for grinding the holes in the sleeves of 
Knight engines. These sleeves have an inside diameter of 
4.250 inches, an outside diameter of 4.6928 inches, and 
they are 18.125 inches long. The hole is said to be ground 
and held within limits of 0.0005 inch, and one machine has 
an output of fifty sleeves for a ten-hour working day. The 







CYLINDER GRINDING 



99 

sleeve is held in a special water-cooled fixture. The water 
enters through the two connections seen at the top, and 
circulates around the outside of the sleeve. This illustra¬ 
tion is from the plant of F. B. Stearns Co., Cleveland, Ohio. 

Fig. 17 illustrates an automobile cylinder grinder in use in 
the Packard plant. The grinding of a six-en-bloc cylinder 
casting is shown. Just above each bore on the fixture there 
is a holder for the diamond wheel-truing tool. 

Grinding Cylinders of Gas Engines and Fire-engine Motors. 
At the plant of John Lauson Mfg. Co., New Holstein, Wis., 


Fig. 18. Grinding a Stationary Gas Engine Cylinder 

cylinders of rather large size are finished by grinding. 
These cylinders are for stationary gas engines, and they are 
from 4 inches in diameter up to 7% inches. Fig. 18 shows 
one of the larger cylinders being ground. The allowance 
for grinding on the smaller sizes varies from 0.008 to 0.010 
inch, and on the larger sizes from 0.017 to 0.020 inch. The 
limit of accuracy is 0.00025 inch, plus or minus. Four-inch 
cylinders for 4- by 5-inch engines are ground at the rate of 
sixteen per day of ten hours, and the 7%-inch size for 7%- 
by 10-inch engines are ground at the rate of ten per day 
of ten hours. While more time is required to finish the cyl- 










100 


CYLINDER GRINDING 


inders by the grinding method than by using some form of 
cutting tool, the new engines operate more economically, as 
better compression is obtained, especially when the engines 
are first put into service. 

The grinding of cylinders for fire-engine motors is il¬ 
lustrated in Fig. 19. These two-en-bloc cylinder castings 
are for 90-horsepower motors. The bore is 6 % inches in 
diameter, and the length of the cylinder is 14 inches. Ten 
cylinders, or twenty holes, are ground per day of ten hours 
and the work is held to a limit of 0.0005 inch. 



Fig. 19. Grinding Cylinder for Fire-engine Motor 

Fixtures for Holding Cylinders while Grinding. The fix¬ 
tures used for holding cylinders during the grinding oper¬ 
ation are usually in the form of an angle-plate. The vertical 
surface of the angle-plate is set perpendicular to the axis 
of the grinding machine spindle, or to the line of the trav¬ 
ersing movement, and the finished face. of the cylinder 
casting is clamped in some way against this vertical surface. 
A type of fixture which has been extensively used is illus¬ 
trated in Fig. 20. This is one of the Heald Machine Co/s 
designs. The cylinder is clamped against the vertical face¬ 
plate by a bar clamp extending across the end, as the illus¬ 
tration shows. This bar clamp is pivoted at the lower end 





CYLINDER GRINDING 


101 


so that it may be readily swung out of the way, and 
the upper end is slotted to receive a second bar to which 
an eccentric clamping lever or handle is pivoted. The spring 
pins located beneath the casting near each end are not 
needed, as the clamp holds the cylinder securely. 

Two plugs may be used to locate the cylinder in horizontal 
and vertical directions, although this is not the general 
practice. One plug is engaged with each end hole or bore, 
and rests upon the lower edge of the rectangular opening 
or slot in the faceplate when the cylinder is in position. 
The cylinder is then shifted until the plug at the left-hand 



Fig. 20. Fixture for holding Cylinders while grinding 


end bears against the end of the slot, after which the work 
is clamped in position for grinding and the plugs are re¬ 
moved. Cylinders having a neck or extension on the flange 
end may be located by the finished surface of this extension. 

Cylinder grinding fixtures are usually provided with dow¬ 
el-pins which engage holes previously drilled and reamed 
in the flange or crankcase end. All of the fixtures which 
may be used for boring, reaming, and grinding are pro¬ 
vided with dowel-pins located in corresponding positions. 
Two holes are usually employed for locating purposes, and 
the dowel-pins on each different fixture that may be used 
engage these same holes. 




102 


CYLINDER GRINDING 


The special design of fixture shown in Fig. 21 is for hold¬ 
ing the sleeves of Knight motors while grinding them in¬ 
ternally. This fixture is practically the same type as the 
one shown in Fig. 16. It is surrounded by a water jacket 
connecting with the two pipes shown. The water is not 
allowed to flow into the inside of the sleeve, but is simply 
circulated around it, in order to prevent the sleeve from 
being overheated and distorted during the grinding opera¬ 
tion. The sleeve is held in place by a swinging end clamp 
which is pivoted at the base of the fixture, and is tightened 
against the work by the small thumb-screw seen at the top. 



Fig. 21. Fixture for holding Sleeves of Motors 


Fixture for Airplane Engine Cylinders. The fixtures for 
holding an airplane engine cylinder must be carefully de¬ 
signed to prevent any distortion of the cylinder as the result 
of improper clamping or excessive clamping pressure. Fig. 
22 shows a fixture designed by the Heald Machine Co. for 
Liberty motor cylinders. The cylinder which is shown in 
the fixture at the left, is a steel forging having very thin 
walls. The cylinder is surrounded by a sheet-metal water 
jacket which is welded to it by the oxy-acetylene process. 
Not far from the open end of the cylinder there is an exter¬ 
nal flange which is clamped against the vertical faceplate 
of the fixture. This faceplate is bored out to receive the 








CYLINDER GRINDING 


103 



open end, and the cylinder is held in position by collar mounted on a screw, to which a handwheel 
applying the clamping pressure at the head end. is attached. This screw passes through a bar 
The clamping member consists of a loose-fitting which may be swung back out of the way (see 









104 


CYLINDER GRINDING 


right-hand view) for inserting or removing the cylinder. 
Water is circulated through the jacket while grinding, en¬ 
tering at the head end and leaving at the opposite end of the 
jacket. The unjacketed section, adjacent to the open end of 
the cylinder, is flooded on the outside by a short length of 
perforated pipe which may be seen projecting through the 
faceplate of the fixture. This method of cooling has proved 
very effective. 

Cylinder Grinding Attachment. In repair shops where a 
comparatively small number of cylinders may require grind- 



Fig. 23. Engine Lathe equipped with Cylinder Grinding Attachment 


ing and the expense of a special cylinder grinding machine 
would not be warranted, some type of grinding attachment 
may be used. One attachment of this kind, intended for 
application to engine lathes, is illustrated in Fig. 23. The 
wheel-spindle is mounted eccentrically relative to the lathe 
spindle, and it traverses around the cylinder wall slowly 
while revolving rapidly about its own axis, the action being 
similar to that of a regular cylinder grinder. The wheel- 
spindle is driven by the belt seen at the left-hand end of the 
headstock, which connects with an independent countershaft 
and revolves a driving shaft extending through the hollow 




CYLINDER GRINDING 


105 


lathe spindle. This shaft, which is mounted in bronze 
bearings, transmits motion to the grinding-wheel spindle 
through a pair of universal joints. The grinding-wheel 
spindle is carried by a plate which is bolted to the lathe 
faceplate and has an elongated slot on one side so that the 
wheel-spindle may be offset relative to the lathe spindle. 
This eccentric adjustment is made possible by the universal 
joints referred to. When a cylinder is being ground, the 
back-gearing of the lathe is engaged so that the planetary 
motion, or rotation of the wheel-head, is relatively slow, 
while the wheel itself revolves at a peripheral speed varying 
from about 4500 to 5000 feet per minute. The cylinder is 
clamped against an angle-plate, as the illustration shows, 
which, in turn, is bolted to the lathe carriage. The steel 
tubing carrying the wheel is held in an adjustable plate by 
two clamping bolts. By loosening these bolts and removing 
one pin in the universal joints, the tube and the wheel may 
be withdrawn and a boring-bar substituted, in case the 
amount of stock to be removed is sufficient to warrant tak¬ 
ing a boring cut prior to grinding. This attachment is made 
by the Salter Motor Mfg. Co., 1516 Oakland Ave., Kansas 
City, Mo. 

Wheels for Cylinder Grinding. The quality of work and 
the rate of production may both be seriously affected if the 
grinding wheel is not suitable. The selection of grind¬ 
ing wheels varies somewhat according to the ideas 
of different engine manufacturers as to the finish required 
for cylinder bores. A fine light finish is not necessarily an 
indication of accuracy. A coarser and freer cutting wheel 
may not leave quite as much polish in the bore as a harder 
finer wheel, but the chances are that the work is more 
accurate. Then too, a free-cutting wheel grinds faster, 
which is an essential feature. In general, the wheel should 
be as soft as it can be without crumbling or wearing away 
too rapidly under reasonably heavy cuts. Too much atten¬ 
tion is often paid to wheel wear. The extra cut for fairly 
soft wheels may be very small as compared with the increase 
in the production of ground cylinders made possible by the 
use of such wheels. In other words, while the wheel wears 


106 


CYLINDER GRINDING 


faster than one of hard bond, it also cuts faster and does 
more work. Although a wheel of very hard bond would 
last a long time, its rate of production would also be very 
low. Ordinarily the wheel should not be harder than grade 
K according to the Norton system of grading or grade 0 
according to the Carborundum Co/s method. The grain 
usually varies from 36 to 60. A fine wheel is not necessary 
to obtain a good finish if the wheel face is kept true and the 
relative speeds and feeds are suitable. Wheels that are too 
hard and fine represent a much larger percentage of the 
mistakes in wheel selection than those which are too soft 
and coarse. The exact grade and grain should be deter¬ 
mined by actual trial, because of varying conditions. The 
harder and more dense the cutting, the softer the wheel 
should be. A relatively soft wheel is also preferable when 
a liberal allowance has been left for grinding, or when 
grinding a cylinder having thin walls which are easily dis¬ 
torted by the boring operation. In grinding cylinders for 
two-cycle engines having open ports on the side, the bond 
of the wheel should be harder than for a plain cylinder, 
because the edges of the port tend to tear out the abrasive. 
The grade of wheel to use may depend somewhat upon the 
design of the machine or its condition. For instance, a soft 
free-cutting wheel, suitable for a rigid machine without 
play in the grinding spindle or looseness in other working 
parts, might be too soft for a machine which vibrates con¬ 
siderably. The vibration causes the abrasive grains to be 
dislodged more rapidly, and if it cannot be eliminated by 
the adjustment of bearings or slides and is due to the light¬ 
ness of the parts, the remedy is to use either a harder 
wheel or a different machine. Wheels made from abrasives 
belonging to the carbide of silicon group—such as carborun¬ 
dum and crystolon—should be used for grinding cast-iron 
cylinders, but for grinding steel airplane cylinders an alu¬ 
minum-oxide abrasive such as alundum or aloxite is 
preferable. 


INDEX 


Page 

Allowances for cylinder grinding. 85 

Automobile cylinder grinding. 93 

Boring and milling machine, cylinder, combination. 8 

Boring and reaming fixtures. 61 

tools, combination. 55 

Boring attachment, radial, for cylinders. 23 

Boring bars, portable, for cylinder work. 32 

used in engine lathe, for cylinder boring. 30 

Boring cylinders, in engine lathes. 29 

tools for. 34 

Boring four-valve steam engine cylinders. 26 

Boring large cylinders. 25 

Boring machines, cylinder, classes of. 2 

cylinder, double-head, four-spindle. 6 

cylinder, six-spindle. 4 

cylinder, twelve-spindle. 11 

single-spindle, for roughing and finishing. 12 

Boring, rough-, heat-treatment after. 17 

Boring, scleroscope hardness test before. 19 

Clamping wedges, on fixture operated by handwheel. 67 

Clamps, wedge and cam-operated, on fixture. 65 

Combination boring and reaming tools. 55 

Cross adjustment of grinding head on cylinder grinding machine.. 81 

Cutter-heads, adjustable, rigid and floating types. 43 

six-blade, for rough-boring. 35 

Cylinder grinding. 73 

attachment . 104 

Cylinder head, machining. 46 

Cylinder jacket, circulating steam through, while grinding. 84 

circulating water through, while grinding. 83 

Cylinder reamers, Kelly. 53 

McCrosky adjustable. 47 

Cylinders, airplane, grinding. 86 

large boring. 25 

methods of machining bores. 1 

open-end, fixtures for. 68 


107 







































108 INDEX 

Page 

Dry and wet methods of grinding. 85 

Peeding movement of cylinder, relation of, to rotation of wheel- 

head . 82 

Feeds and speeds for reaming. 16 

Finishing reamers, cutting edges of. 58 

floating . 42 

Fixtures, boring and reaming. 61 

boring with movable locating pins. 63 

for cylinders having removable heads. 68 

for holding airplane engine cylinders. 102 

for holding cylinders while grinding. 100 

with removable work-holding slides. 70 

Floating parallel reamer, Martell. 50 

Gisholt shell reamers. 52 

Grinding, advantages of. 74 

attachment for cylinders. 104 

circulating steam through cylinder jacket. 84 

circulating water through cylinder jacket. 83 

fixtures for holding cylinders. 100 

reaming and, reasons for variation in practice... 75 

reaming compared with. 73 

wet and dry methods. 85 

Grinding cylinders. 73 

allowances for. 85 

for airplane engines. 86 

in automobile plants. 93 

wheels for. 105 

Grinding machine, cylinder, with grinding head cross adjustment. 81 

eccentric-head type. 77 

Grinding single-point cylinder boring tools. 29 

Heald cylinder grinder. 79 

Heat-treatment after rough-boring. 17 

Indexing fixture for reaming on single-spindle machine. 71 

Kelly cylinder reamers. 53 

Lap for cylinders, design of. 20 

Lapping cylinders, machine for. 19 

Lathes, engine, used for cylinder boring. 29 

Locating pins, movable, on boring fixture. 63 

Martell floating parallel reamer. 50 

McCrosky adjustable cylinder reamers. 47 

Morse shell drill, for roughing cylinder bores. 56 









































INDEX 


109 

O Page 

pen-end cylinders, fixture for. 68 

Peerless shell reamers, expansion type. 57 

Pilots for cylinder reamers. 59 

Radial boring attachment for cylinders. 23 

Reamers, cylinder, Kelly. 53 

cylinder, pilots for. 59 

eight-blade, used prior to grinding. 39 

finishing, cutting edges of. 58 

floating finishing. 42 

Gisholt shell. 52 

heating, to avoid errors due to expansion. 15 

Martell floating parallel. 50 

McCrosky adjustable, cylinder. 47 

rigid and floating types.. 49 

Reaming and boring fixtures. 61 

Reaming and grinding, reasons for variations in practice. 75 

Reaming, cylinders, tools for. 34 

finish, on single-spindle machine. 13 

grinding, compared with. 73 

indexing fixture for, on single-spindle machine. 71 

objections to. 74 

use of single-point tool prior to. 43 

speeds and feeds for. 16 

Rolling, cylinder, tool for. 22 

Rolling or planishing method of finishing bores. 20 

Rough-boring, adjustable tool for. 41 

four-blade tool for. 39 

heat-treatment after. 17 

six-blade cutter-heads for. 35 

six-blade tool for. 39 

Scleroscope, hardness test before boring... 19 

Shell drill, Morse, for roughing cylinder bores. 56 

Shell reamers, expansion type of. 57 

Gisholt . 52 

Single-spindle machine, finish-reaming on. 13 

rough- and finish-boring on. 12 

Six-spindle cylinder boring machines. 4 

Speeds and feeds for reaming. 16 

Steam engine cylinders, four-valve, boring. 26 

Straightening bore with two-blade tool. 37 










































110 INDEX 

Page 

Tools, adjustable, for rough-boring. 41 

eight-blade, for reaming cylinders. 39 

for boring and reaming cylinders. 34 

four-blade, for rough-boring cylinders. 39 

single-point cylinder boring, grinding. 29 

single-point, used prior to reaming. 43 

six-blade, for rough-boring cylinders. 39 

two-blade, for straightening bore. 37 

Twelve-spindle cylinder boring machine. 11 

Wet and dry methods of grinding. 85 

Wheel-head, rotation of, related to feeding movement of cylinder. 82 
Wheels for cylinder grinding. 105 














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-Machinery announces a new and original series of Dollar 
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MACHINERY’S DOLLAR BOOKS 

Shop Arithmetic for the Machinist. 

Solution of Triangles. 

Gear-cutting and Gear-cutting Machines. 

Broaching Practice. 

Cylinder Boring, Reaming, and Grinding. ^ 

Planning and Controlling Production. 

Employment Management, Wage Systems, and Rate 
Setting. 

Ball and Roller Bearings. 

Bearings and Bearing Metals. 

Principles of Mechanics and Strength of Materials. 
Practical Problems in Mathematics. 

Cutting Compounds and Distributing Systems. 

Die Casting. 

Drop Forging and Drop Forging Dies. 

Machine Forging. 

Blacksmith Shop Practice. 

Modern Apprenticeships and Shop Training Methods. 
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Die-making and Die-design 

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